South Korean government on Monday refused to give in to doctors' protests against its plan to increase the medical school enrollment quota, as the threat of the mass suspension of medical licenses for striking trainee doctors loomed over the country.

Second Vice Health Minister Park Min-soo said the government is moving to take "irreversible" measures against trainee doctors who left work, warning of suspensions of their medical licenses for at least three months.

"If (the licenses of trainee doctors) are suspended for three months, they will not be able to fulfill the requirements for their training period, which would lead them to become certified specialists at least a year late," he said, urging the doctors to return to work. Of the some 8,945 trainee doctors who left work as of Monday, accounting for 72 percent of all interns and residents, only 565 have returned.

The ministry's order is based on Article 59 of the Medical Service Act, which stipulates that the minister of health and welfare can issue an order to medical institutions or personnel to resume medical services, if there is a reasonable ground to believe that a suspension of medical services is likely to cause "great difficulties in giving medical treatment to patients."

Refusal to comply without justifiable cause can be punished by up to a one-year suspension of practicing medicine for doctors. It can also be subject to criminal punishment of up to a 30 million won ($22,500) fine.

The possibility of criminal punishment is a pressing matter for the doctors on strike, as recently revised Article 8 of the Medical Service Act states criminal punishment as one of the grounds for disqualification from practicing medicine. It states that any doctor who received a criminal punishment of imprisonment without labor or greater can have one's license revoked.

Those sentenced to a suspended term or suspended sentence are also subject to this clause, meaning a doctor can be stripped of their ability to practice medicine for relatively minor crimes.

The ministry would not even have to rely on the justice system to take away the striking doctors' medical licenses, as a physician who has been suspended three times by the ministry can have his or her license revoked. It has already vowed to take both administrative and legal measures against the trainee doctors.

When a physician's medical license is revoked and they wish to get back the license, they must complete at least 40 hours of class on a range of topics including understanding of medical law, the role and ethics of medical personnel and understanding patients' rights. But in order to reapply for the license, the doctor must also go through a process by which the Health Ministry reviews and deliberates over whether to reinstate them.

The ministry's guidelines state that for reapplication, either the grounds for the initial cancellation of the license must have been eliminated. Or the doctor must clearly show signs of remorse.

From 2014 to June last year, 526 doctors whose licenses were taken away had applied for a new license, but only 209 were reinstated as state-certified physicians.