South Korea said Monday it had started procedures to suspend the medical licences of 4,900 junior doctors who have resigned and stopped working to protest government medical training reforms, causing healthcare chaos.

The walkout, which started February 20, is over government plans to sharply increase the number of doctors, which it says is essential to combat shortages and South Korea's rapidly ageing population, while the medics argue it will erode service quality.

Nearly 12,000 junior doctors -- 93 percent of the trainee workforce -- were not in their hospitals at the last count, despite government back to work orders and threats of legal action, forcing Seoul to mobilise military medics and millions of dollars in state reserves to help.

The Health Ministry on Monday said it had sent administrative notifications -- the first step to suspending the doctors' medical licences -- to thousands of trainee doctors after they defied specific orders telling them to return to their hospitals.

"As of March 8 (notifications) have been sent to more than 4,900 trainee doctors," Chun Byung-wang, director of the health and medical policy division at the health ministry, told reporters.

The government has previously warned striking doctors they face a three month suspension of their licences, a punishment which, it says, will delay by at least a year their ability to qualify as specialists.

Chun urged the striking medics to return to their patients.

"The government will take into account the circumstance and protect trainee doctors if they return to work before the administrative measure is complete," he said, indicating doctors who come back to work now could avoid the punishment.

"The government will not give up dialogue. The door for dialogue is always open ... The government will respect and listen to opinions of the medical community as a companion for the medical reforms," he added.

Military mobilised 

The government last week announced new measures to improve pay and conditions for trainee medics, plus a review of the continuous 36-hour work period, which is a major gripe of junior doctors.

The strikes have led to surgery cancellations, long wait times and delayed treatments at major hospitals.

Seoul has mobilised military doctors and earmarked millions of dollars of state reserves to ease service shortfalls, but has denied that there is a full-blown healthcare crisis.

Military doctors will start working in civilian hospitals from Wednesday this week, Chun said.

Under South Korean law, doctors are restricted from striking, and the health ministry has asked police to investigate people connected to the work stoppage.

The government is pushing to admit 2,000 more students to medical schools annually from next year to address what it calls one of the lowest doctor-to-population ratios among developed nations.

Doctors say they fear the reform will erode the quality of service and medical education, but proponents accuse medics of trying to safeguard their salaries and social status.