Two-thirds of the country's residents and intern doctors have walked off the job to protest a plan to raise the number of students admitted to medical school each year by 2,000 in a bid to address what the government says is a shortage of doctors.

As of Wednesday, only 294 of the more than 9,000 trainee doctors who have left their posts were back at work, Vice Health Minister Park Min-soo told a briefing.

"It is fortunate there are trainee doctors returning to patients' side and I'd say they made the wise decision," said Park.

The young doctors who are protesting say the government should first address pay and working conditions before trying to increase the number of physicians.

The government has said its package of healthcare reforms includes many of the demands of the medical community such as expanded legal protection in malpractice cases and better pay for doctors in essential services.

The government has issued a back-to-work order to doctors who have walked out and warned their medical licences could be suspended if they do not comply by Thursday's deadline.

The walkout has caused disruption at some hospitals which were forced to turn away some patients and cancel surgeries and medical procedures.

The government has invited the trainee doctors to a meeting later on Thursday in a bid to persuade them to return.

There have been no formal discussions so far and the government has said the Korean Medical Association, which represents mostly private practitioners, was not the right body to address the trainee doctors' concerns.

(Reporting by Jack Kim; Editing by Ed Davies and Michael Perry)