Hundreds of junior doctors offered hospital positions have had their job offers rescinded after a mistake was discovered in the recruitment process.
The Royal College of Physicians (RCP) said it would have to rerun the offers process, blaming human error and branding it a "dreadful situation".
Junior medics entering their third year of specialist training now face losing the positions they had originally been offered, with many having already made plans to start the jobs in just a few months' time.
The British Medical Association (BMA) said it was "appalled" to discover the blunder, and that it had caused "extreme anxiety" for trainees.
Those affected had been offered jobs in 24 different fields through ST3 Recruitment, a nationally co-ordinated system for recruiting doctors.
But last week the RCP discovered some candidates had been given the wrong interview marks following an error in transferring data from one computer program to another, leading to a "significant number" of incorrect rankings.
In a letter to all those with offers, the RCP said: "We are deeply sorry that it has been necessary to rerun the ST3 offer process due to a mistake in this round of processing.
"We have taken this approach to be fair to all candidates which can only be achieved with the real scores used."
In a joint statement, the chairman of the BMA council Chaand Nagpaul, and the chairman of the BMA junior doctors committee Jeeves Wijesuriya, said they had spoken to RCP president Professor Jane Dacre to "articulate the strength of feeling and extent of the impact that this has had".
They said: "We have heard from trainees who have, after receiving these job offers, put down deposits on homes, arranged moves or whose families had adjusted their plans."
The statement added: "We cannot express how unacceptable we find this situation and the impact - both emotionally and financially - it is having on junior doctors across the UK."
The RCP said it would do its "utmost" to resolve the cases of those who had accepted offers and made "unretractable commitments" based on those offers.
"We set the highest standards for our work and expect to be held to them," it said.
"We have not met them here and are truly sorry. We will learn from our mistake and make any changes necessary to fix it."
The offers process will begin again on May 14.