Doctors at medical facilities across South Korea walked off the job in a one-day strike on Tuesday, dramatically if briefly expanding a months-old protest against the government’s health care policies that began when residents and interns at major hospitals stopped working in February.

       The physicians taking part in the one-day strike belong to the country’s biggest doctors’ group, the Korean Medical Association, which has about 140,000 members. It was not immediately clear how many were participating, but its membership recently voted three-to-one in favor of collective action, according to the group. Thousands of its members rallied in Seoul on Tuesday afternoon.

       South Korea’s president, Yoon Suk Yeol, called the latest walkout “very disappointing and unfortunate” in a televised cabinet meeting on Tuesday morning. It came a day after hundreds of medical professors at Seoul National University Hospital and other major facilities began an indefinite work stoppage.

       “I have a bad liver and came to get an ultrasound,” Yang Myoung-joo, 84, a patient at Seoul National University Hospital, said on Tuesday. She said her appointment had been canceled with no new date provided. “Doctors deal with people’s lives. Is going on strike the right thing to do?”

       The dispute began in January, when Mr. Yoon’s government announced new health care policies that included a plan to dramatically expand admissions to medical schools. Physicians say the plan was drafted without consulting them and would not solve the health care system’s problems. But the government says more doctors are badly needed in South Korea, which has fewer per capita than most developed nations.

       More on South Korea An Impeachment Threat: President Yoon Suk Yeol has been accused of intervening in an inquiry into an accidental death during a peacetime search and rescue operation.

       Standoff With Doctors: South Korea’s health care system has been in disarray because thousands of doctors walked off the job after the government proposed to drastically increase medical school admissions. Public opinion has now turned against the government.

       Parliament Election: South Koreans delivered a stinging defeat to President Yoon Suk Yeol and his party, giving the opposition one of its biggest electoral victories in recent decades and pushing Yoon to the verge of being a lame duck.

       A K-Pop Controversy: Hybe, the firm behind BTS, has lost hundreds of millions of dollars in market value because of an unusually public and hostile feud with the producer of NewJeans, arguably today’s hottest K-pop act.

       Neither side has given much ground. In May, the government set the medical school admissions quota for the 2025 school year at 4,570 students, an increase of about 1,500 — fewer than the 2,000 originally proposed, but still a dramatic jump. That announcement appeared to be the trigger for the most recent labor actions.

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