Thousands of doctors hoping to move to Britain to work have had their examinations cancelled owing to a rise in Covid-19 cases.
The General Medical Council said there was a shortage of doctors to invigilate the exams, which most doctors who qualified outside the UK must take.
More than 2,600 medics from other countries had been preparing to sit the tests in January and February.
The GMC said staff absences related to the pandemic meant doctors who had been due to assess the students could not be spared.
It comes as the UK recorded more than 150,000 deaths related to Covid-19 on Saturday, the highest in Europe.
“As cases of Covid-19 rise, staff absence across primary and secondary care providers is increasing, and the availability of our own staff and test centre role players is being significantly affected,“ the GMC said.
“The dozens of medical examiners who would normally be supervising our tests each day are also needing to rightly prioritise clinical work.
“In order to help support our health services through this latest wave, and to minimise risk to staff and candidates, in February we’ll be running tests just for candidates already in the UK or with an offer of employment. To do that, we need to cancel tests currently scheduled for January and February 2022 and rearrange them for later in the year.
“We know this will be difficult news for those candidates but it’s important we take this action now as we wait to understand more about the impact of the Omicron variant.”
More than 50 doctors and support staff would have been needed to work each day.
The chairman of the British Association of Physicians of Indian Origin has called for overseas doctors affected by the cancellations to be given financial and emotional support.
The association says many have been left stranded and are facing significant hardship.
“This sort of action by the GMC only serves to give the wrong perception to migrant doctors in this country, as well as those who intend to come and serve in the NHS,” JS Bamrah said.
Bapio president Dr Ramesh Mehta said the move would deprive the UK of the “timely recruitment” of valuable doctors.
“The cancellation of GMC examinations is worrying,” Bapio joint secretary Dr Biju Simon said.
“Many young doctors already sacrificed their time and money to be here in the UK, despite the uncertainties of the Covid-19 pandemic. The cancellation of the tests amplifies the agony, adding further psychological torment and financial deficit.”
The GMC said new dates would be announced, enabling candidates to take their exams in the summer.
Hundreds of British troops have been stationed in hospitals in London to support the National Health Service owing to staff shortages caused by Covid-19.
About 200 armed forces personnel are being made available to hospitals in the UK capital, which has been the centre of the Omicron outbreak.
NHS England is experiencing the highest number of Covid absences since the vaccine rollout, with more than 40,000 staff unable to attend work on two days last week.