The Home Office is systematically barring young children from joining their mothers in Britain despite extensive proof the women are their primary caregivers, an Observer investigation has revealed.

Under an opaque policy condemned as discriminatory and “inhumane”, the government has refused dozens of visas for children of migrant single mothers, many of whom came to work in the NHS or social care, saying there are “no compelling reasons” to grant them.

The women left their children – some as young as two – in the temporary care of relatives or friends while they moved to Britain from countries including Zimbabwe, Zambia, Kenya, South Africa and India.

Before leaving, they say, they had been reassured by their employers that their children would be able to follow, in line with current immigration rules permitting healthcare workers to bring close family members. But when they applied for the children’s visas, the applications were rejected.

In refusal letters seen by the Observer, the Home Office questioned why the children could not stay permanently with their grandparents or other relatives. In other cases, it said there was no reason why they could not go to live with their fathers, even though their mothers had sole custody or the fathers had not seen the children for years. Many of the letters, addressed directly to the children, conclude: “It was your mother’s personal decision to depart for the UK and you have not provided sufficient evidence to grant your visa on serious or compelling grounds.”

The cases have come to light weeks after the government announced a plan to slash immigration by placing restrictions on the dependants of migrant healthcare workers. Under controversial rules expected to be introduced this spring, care workers coming to the UK will be barred from bringing family members, while other health workers will have to earn £29,000 a year, rising to £38,700 in 2025, to be permitted to do so.

But scores of applications from such workers are already being quietly refused. The Observer has examined 10 cases, and been alerted to 140 more, where migrant women, all single mothers, have had visas for children denied in the past 18 months.

The applications have not been rejected because the Home Office doubts they are genuine or that the women are the children’s primary caregivers. Instead, they have been refused under a Home Office rule that a child may only be given a visa if both parents are living in the UK, unless the parent living here has “sole responsibility”.

The policy means single parents are required to prove not only that they have sole custody but that the other parent is not involved in their child’s upbringing – something experts say can be hard to do.

If the sole responsibility threshold is not met, the Home Office can still grant applications if it believes there are compelling or compassionate grounds.

But as yet, it has declined to do so in the women’s cases investigated by the Observer, which has seen extensive evidence to support the mothers’ claims that they are their children’s sole caregivers.

In many cases, the women gave the Home Office court documents and custody papers proving they were the sole custodian, as well as bank statements, insurance policies, photos and letters of support from schools, doctors and church leaders.

Many also have signed consent letters from their children’s fathers, but in some cases this has been used against them. One mother, Getty, had a visa for her six-year-old daughter denied. The care worker from Zambia says she and the girl’s father separated when she was pregnant and she has always been her sole caregiver.

Shortly after she arrived in Britain in March, Getty, 36, submitted an application for her child to join her. She supplied documents including a court order linked to her separation and an affidavit from the girl’s father saying it would be in the child’s best interests to come to Britain. But the Home Office refused the child a visa, saying the fact her father had provided a consent letter was proof he was still in her life and could therefore look after her.

Getty said the separation had taken a huge toll, adding: “My daughter asks me every day when her papers are going to be ready. I have to be honest with her and tell her: ‘I’m still waiting.’ She is only used to living with me. It’s really, really hard.”

In another case, an NHS nurse who provided the Home Office with a court document proving she had sole custody for her two daughters, aged four and 13, was told there were no “serious or compelling reasons” why the girls needed to join her. “It’s heartbreaking. How can I sleep at night?” she said. “I am the mother of the children and I have always looked after them.”

Patricia Chinyoka, chief executive of the Women of Zimbabwe project, which is supporting many of the women, described the refusals as “absolutely appalling”.

“Some of the women have supplied an amazing array of proof and then they still get a letter saying: ‘We don’t believe you.’ They have sold properties, left jobs – they’ve sold up and come here and this is what they are now faced with,” Chinyoka said. “They don’t know what to do.”

It is not the first time the sole responsibility test has faced scrutiny. In November, a Kenyan expert in world literature at Bristol University was refused a visa for her six-year-old daughter. The decision was later reversed. In 2019, two other similar cases were also reversed.

Sairah Javed, a solicitor at the Joint Council for the Welfare of Immigrants, said a helpline the campaigning charity runs with the Unison trade union had seen a “categoric rise” in such refusals in recent months, with about 20 last year compared with five in previous years.

Most related to single mothers in the healthcare sector. “We’re seeing a lot of pain and heartache for people who have come to the UK in accordance with all our rules,” Javed said. “It’s quite inhumane. It’s just another form of assault on family values.”

Liberal Democrat peer Sally Hamwee, chair of the justice and home affairs committee in the Lords, called for the policy to be revised. Lady Hamwee said: “It does not recognise how families operate in the 21st century and is causing huge distress and harm to adults and children who are swept up in it.”

The Home Office said it could not comment on individual cases. It said: “The sole responsibility rule is a long-term government policy and all visa applications are carefully considered on their individual merits in accordance with immigration rules.”

Under an opaque policy condemned as discriminatory and “inhumane”, the government has refused dozens of visas for children of migrant single mothers, many of whom came to work in the NHS or social care, saying there are “no compelling reasons” to grant them.

The women left their children – some as young as two – in the temporary care of relatives or friends while they moved to Britain from countries including Zimbabwe, Zambia, Kenya, South Africa and India.

Before leaving, they say, they had been reassured by their employers that their children would be able to follow, in line with current immigration rules permitting healthcare workers to bring close family members. But when they applied for the children’s visas, the applications were rejected.

In refusal letters seen by the Observer, the Home Office questioned why the children could not stay permanently with their grandparents or other relatives. In other cases, it said there was no reason why they could not go to live with their fathers, even though their mothers had sole custody or the fathers had not seen the children for years. Many of the letters, addressed directly to the children, conclude: “It was your mother’s personal decision to depart for the UK and you have not provided sufficient evidence to grant your visa on serious or compelling grounds.”

The cases have come to light weeks after the government announced a plan to slash immigration by placing restrictions on the dependants of migrant healthcare workers. Under controversial rules expected to be introduced this spring, care workers coming to the UK will be barred from bringing family members, while other health workers will have to earn £29,000 a year, rising to £38,700 in 2025, to be permitted to do so.

But scores of applications from such workers are already being quietly refused. The Observer has examined 10 cases, and been alerted to 140 more, where migrant women, all single mothers, have had visas for children denied in the past 18 months.

The applications have not been rejected because the Home Office doubts they are genuine or that the women are the children’s primary caregivers. Instead, they have been refused under a Home Office rule that a child may only be given a visa if both parents are living in the UK, unless the parent living here has “sole responsibility”.

The policy means single parents are required to prove not only that they have sole custody but that the other parent is not involved in their child’s upbringing – something experts say can be hard to do.

If the sole responsibility threshold is not met, the Home Office can still grant applications if it believes there are compelling or compassionate grounds.

But as yet, it has declined to do so in the women’s cases investigated by the Observer, which has seen extensive evidence to support the mothers’ claims that they are their children’s sole caregivers.

In many cases, the women gave the Home Office court documents and custody papers proving they were the sole custodian, as well as bank statements, insurance policies, photos and letters of support from schools, doctors and church leaders.

Many also have signed consent letters from their children’s fathers, but in some cases this has been used against them. One mother, Getty, had a visa for her six-year-old daughter denied. The care worker from Zambia says she and the girl’s father separated when she was pregnant and she has always been her sole caregiver.

Shortly after she arrived in Britain in March, Getty, 36, submitted an application for her child to join her. She supplied documents including a court order linked to her separation and an affidavit from the girl’s father saying it would be in the child’s best interests to come to Britain. But the Home Office refused the child a visa, saying the fact her father had provided a consent letter was proof he was still in her life and could therefore look after her.

Getty said the separation had taken a huge toll, adding: “My daughter asks me every day when her papers are going to be ready. I have to be honest with her and tell her: ‘I’m still waiting.’ She is only used to living with me. It’s really, really hard.”

In another case, an NHS nurse who provided the Home Office with a court document proving she had sole custody for her two daughters, aged four and 13, was told there were no “serious or compelling reasons” why the girls needed to join her. “It’s heartbreaking. How can I sleep at night?” she said. “I am the mother of the children and I have always looked after them.”

Patricia Chinyoka, chief executive of the Women of Zimbabwe project, which is supporting many of the women, described the refusals as “absolutely appalling”.

“Some of the women have supplied an amazing array of proof and then they still get a letter saying: ‘We don’t believe you.’ They have sold properties, left jobs – they’ve sold up and come here and this is what they are now faced with,” Chinyoka said. “They don’t know what to do.”

It is not the first time the sole responsibility test has faced scrutiny. In November, a Kenyan expert in world literature at Bristol University was refused a visa for her six-year-old daughter. The decision was later reversed. In 2019, two other similar cases were also reversed.

Sairah Javed, a solicitor at the Joint Council for the Welfare of Immigrants, said a helpline the campaigning charity runs with the Unison trade union had seen a “categoric rise” in such refusals in recent months, with about 20 last year compared with five in previous years.

Most related to single mothers in the healthcare sector. “We’re seeing a lot of pain and heartache for people who have come to the UK in accordance with all our rules,” Javed said. “It’s quite inhumane. It’s just another form of assault on family values.”

Liberal Democrat peer Sally Hamwee, chair of the justice and home affairs committee in the Lords, called for the policy to be revised. Lady Hamwee said: “It does not recognise how families operate in the 21st century and is causing huge distress and harm to adults and children who are swept up in it.”

The Home Office said it could not comment on individual cases. It said: “The sole responsibility rule is a long-term government policy and all visa applications are carefully considered on their individual merits in accordance with immigration rules.”