A Singaporean doctor who has been in Britain for almost 10 years may be forced to leave after applying for a visa renewal three weeks late.

Dr Luke Ong, 31, arrived in the country in September 2007 to study medicine at the University of Manchester. After completing the five-year course in 2012, he extended his student visa to August 2017 so he could train to become a general practitioner.

But in Sept 2017, five months short of completing his training, his application for indefinite leave to remain was rejected by Britain's Home Office, Dr Ong told The Straits Times in a phone interview on Monday (April 9).

Dr Ong made the formal application for indefinite leave on Sept 2, 18 days after the deadline.

He first attempted to book an appointment to secure his status in July, but was told that the closest available date was Sept 2.

He was also told that the appointment for the indefinite leave application had to be made within 28 days of his 10-year anniversary of being in Britain. As a result, the earliest he could have applied was on Aug 16 - the day after his visa expired.

While he could have extended his student visa in the meantime, he would have had to send his passport and personal documents in the post.

Asked if he went with this option and why, Dr Ong said he chose instead to wait for the Sept 2 appointment but when he attended it, he was told that his application had been turned down as he was in breach of the immigration law.

Dr Ong appealed against the decision and a judge ruled in his favour, agreeing that his removal would breach his human rights and that it "would not be proportionate".

But the Home Office is seeking leave to appeal against that ruling, according to a Daily Mail report on Sunday (April 8).

"I really cannot explain this. There aren't enough GPs here, it takes two weeks to see one, and I'm just a few months away from qualifying," said Dr Ong.

Last year, the National Health Service (NHS), Britain's publicly-funded healthcare system, announced plans to increase the number of GPs by accelerating an international recruitment programme. As part of the initiative, the NHS plans to spend £100 million (S$185 million) to bring in 3,000 GPs from abroad. Recruitment agencies will earn about £20,000 ($37,000) for each GP successfully placed in Britain.

The British Medical Association (BMA) has condemned the Home Office's decision, calling it "utterly incomprehensible".

"This situation, in which a doctor who has committed the last 10 years of his life studying, training and serving in the NHS faces deportation over what appears to be an honest oversight, beggars belief at a time when the government is prepared to spend millions recruiting GPs from abroad," said BMA council chairman Chaand Nagpaul.

He also called for the Home Office to "move away from this hostile culture" regarding immigration rules.

"The government knows there is a serious shortage of GPs in England, with too few medical students opting for the specialism... something which is having a negative effect on patient care," he said.

The Royal College of GPs, Dr Ong's MP Lucy Powell and Manchester mayor Andy Burnham have also backed him, The Daily Mail reported on Tuesday.

A Home Office spokesman told The Straits Times on Tuesday that the case is under appeal and it would not be able to comment.

It is clear that Britain is now home for Dr Ong. He said: "All my friends are here.

"I've got two half-brothers from my dad's first marriage who are based here in London as well. My life revolves around what I have here in Manchester."

A petition he launched on Change.org has received over 45,000 signatures.

If he must leave Britain, he plans to either return to Singapore, where his parents and grandparents are, or to head to Australia.

"It's a very hostile environment here for immigrants," he said. "Not just refugees, but also highly skilled migrants - what happened to me isn't uncommon."

Last year, two Malaysian doctors had their visa applications rejected and were told to leave the country.

In both cases, the Home Office's decisions were eventually overturned.