The Health Ministry ordered 221 hospitals on Friday to ban mass leave of junior doctors and to maintain essential medical personnel, in response to a nationwide movement of collective action among doctors in protest of the government's recent decision to increase the medical school enrollment quota.

The government's decision comes after trainee doctors from five major general hospitals in Seoul threatened to walk off the job at 6 a.m. on Tuesday next week, in an apparent show of protest against Seoul's new policy announced last week to expand the medical school quota by 2,000 from the current 3,058 seats.

The five hospitals are Asan Medical Center, Samsung Medical Center, Severance Hospital, Seoul National University Hospital and Seoul St. Mary's Hospital, which combined account for 15 percent of total medical residents in the country.

Residents and interns leaving the job at large hospitals is expected to impact the nation's health care system significantly, as they are essential workers for critical patients. The impact is feared to be greater than that of doctors leaving their positions at small clinics, according to observers.

The Health Ministry warned it will conduct on-site inspections of hospitals where doctors are found to have failed to report for work and issue orders to individuals to resume work, while taking corresponding legal measures against doctors who violate such orders by refusing.

According to the Medical Service Act, if a group of doctors refuses to provide treatment, they can be ordered to commence work. Those who do not comply with the order could face imprisonment for up to three years. Doctors sentenced to time in jail could lose their licenses.

As of Thursday midnight, seven other hospitals, including Wonkwang University Hospital, Gachon University Gil Medical Center and Korea University Guro Hospital, had already received a combined 154 resignation letters, all of which have yet to be accepted, according to the ministry.

Meanwhile, 35 out of 40 medical schools held an emergency meeting Thursday and decided to submit an en masse leave of absence next Tuesday. Seniors at Hallym University College of Medicine have already announced they a one-year leave of absence.

The Education Ministry established a task force and activated an emergency contact system with the 40 medical universities nationwide on Friday to monitor students' trends and counteractions at all times.

"We ask each university to thoroughly guide students and manage academic affairs by complying with relevant laws and regulations in response to the collective behavior of medical students," the government said at an emergency meeting held by the vice minister of the Education Ministry on Friday.