The Medical Professors Association of Korea said late Wednesday that it has decided to join the one-day shutdown of services on June 18 planned by the largest doctors' group here.

Kim Chang-soo, a preventative medicine and public health professor at Yonsei University who heads the group of professors at 40 medical schools, said medical professors will take a day off next week to demand the scrapping of the medical school quota hike. They have continuously demanded that the government scrap its hike plan for the 2025 school year and discuss an appropriate increase from scratch.

Kim, however, noted that it remains uncertain how many will actually join the strike as the association will "not force" them to do so, adding that the course of action will be decided by each university and professor, not the association.

On Sunday, the Korean Medical Association -- the largest coalition of doctors' groups with approximately 140,000 members, mostly private practitioners -- announced its plan for its members to shut down their services and rally, warning of a "full-fledged battle" against the government to halt its medical school enrollment increase plan.

Earlier in the day, the emergency committee of medical professors at Yonsei University said they would hold an indefinite walkout starting June 27. Yonsei medical professors double as senior doctors at Severance Hospital in Seoul's Seodaemun-gu, Gangnam Severance Hospital and Yongin Severance Hospital. However, emergency rooms and intensive care units will remain in operation, as will treatment for severely ill hospitalized patients.

Their peers at the University of Ulsan will also survey their faculty members until Wednesday afternoon to decide on their future course of action.

In addition, the emergency committee of medical professors at the Catholic University of Korea plans to make its decision about an indefinite walkout sometime next week.

Amid the monthslong standoff between the government and the medical community, the association of patients with severe illnesses on Wednesday urged doctors to keep providing medical treatment instead of going on strike.

"Medical professors at Seoul National University are not professors who just make money but are professors at a national university, which is operated by taxpayers' money," the association said in a conference held in front of the Seoul National University Hospital in Seoul.

Last week, the emergency committee of SNU and SNUH said it has decided to indefinitely suspend outpatient treatment and surgeries beginning June 17.

The association also referred to the shutdown of services as a "decision that ignores the doctors' responsibility and duty to the people," arguing that medical professors are joining the action just to look out for their own interests.

"Severely ill patients are falling into despair, letting go of the hope to survive and being in fear of death every day. ... With the strike, severely ill patients are being thrust into death," the group said, expressing hope that medical professors would backtrack from walking out indefinitely.