A leading children’s psychiatrist plans to quit the NHS and move to Australia because of the Home Office’s “almost callous” refusal to let his mother stay in Britain.

Dr Nishchint Warikoo, the lead psychiatrist for child and adolescent mental health services (CAMHS) in Hampshire, said he and his family were being “forced to leave” the UK in order to stay together.

Warikoo is angry and frustrated that several years of representations have failed to persuade the Home Office to allow his 71-year-old Indian-born mother, Phoola, to remain in Britain. The 46-year-old was also born in India but became a British citizen in 2014 and has lived in the UK and worked in the NHS for 15 years.

Warikoo has argued that because he is her only child and she is widowed and has no family in India who could look after her, she should be allowed to stay so he can take care of her.

Warikoo has appealed directly to Boris Johnson and the home secretary, Priti Patel, to help resolve the situation. He tweeted them on Monday asking for help. “I am a British citizen, NHS consultant, and a researcher. Have cared for thousands of children with mental health problems, saved many young lives and helped thousands of families in distress. Now my family is forced to leave the country. Help please.”

Warikoo has resolved that if the Home Office does not decide on his mother’s case by December, or if they refuse her leave to remain, he, his wife, their British-born 13-year-old daughter and his mother will leave before Christmas.

The application for Phoola Warikoo to remain is also based on a section of the immigration rules which says that somone can be allowed to stay if a child – in this case her granddaughter Soham – would be left in distress if they did not do so.

“Her [his mother] leaving the country would cause severe distress to a child – Soham – directly as she will be separated from her grandmother and indirectly as she [Soham] will be uprooted from her home country”, added Warikoo.

He has already been offered a job and immediate permanent residency for himself, his wife and daughter in Australia, and a visa for his mother to stay in the country.

Warikoo told the Guardian: “It’s very stressful for us as a family. We don’t want to leave the country. But we are being forced to because we are in this limbo state. The Home Office have displayed an almost callous attitude to this case.

“I need to know as soon as possible if my mother is going to be allowed to stay or not, because I can’t take this any more. I have worked so hard for young people and families in Britain in my time here and now I want some support from the system for my family, for it to show a bit of flexibility.”

Last week the Home Office backtracked on a plan to deport a Taiwan-born but British-educated and NHS-funded GP trainee, Dr Mu-Chun Chiang, for making a minor error in her application for a Tier 2 working visa. Medical groups, including the Royal College of GPs, criticised its initial decision as “ludicrous”, heavy-handed and short-sighted, given the deepening shortage of family doctors across the NHS.

The Guardian reported this week how CAMHS services are among the areas of mental healthcare that are struggling with a growing lack of specialist psychiatrists.

For years, Warikoo’s mother visited him on six-month visitor’s visas. However, she may no longer qualify for them because she had applied for leave to remain, he said.

A spokesman for Sussex Partnership NHS mental health trust, where Warikoo works, said: “Dr Nishchint Warikoo is a valued member of our team and a highly regarded consultant psychiatrist. As his employer, we are offering every support we can during this difficult time for him and his family.”

Colleagues have voiced outrage on social media that he may leave Britain and asked the health secretary, Matt Hancock, and the bosses of NHS England to help. One tweeted: “This is just unbelievable. We have a crisis with the CAMHS workforce in this country already. Can we really afford to lose dedicated consultants like Nishchint?”

Another said: “This is absolutely ridiculous. Someone needs to take action and fast. Our mental health system will cripple and lives will be at risk.”

A Home Office spokesperson said: “All visa applications are considered on their individual merits and on the basis of the evidence available. This case is under review and we will be in contact with the applicant in due course.”