The antitrust regulator launched an on-site inspection into a major lobby group for doctors Wednesday for allegedly forcing its members to join a walkout against the government's medical reform plan, officials said.

The Fair Trade Commission sent inspectors to the office of the Korean Medical Association in Seoul and conducted a probe regarding the KMA-led one-day walkout on Tuesday that involved community doctors and other medical staff, as well as a massive rally in Seoul, according to officials of the Fair Trade Commission.

The health ministry earlier this week referred the KMA to the regulator for its possible violation of the fair trade law by allegedly forcing its members to take part in the collective action.

Under the law, business associations are banned from unfairly interrupting the business activities of its members or restricting competition.

Any violation is subject to up to a fine of 1 billion won ($724,585) for the organization. Organization chiefs or other individuals in charge can face up to 200 million won in fines or three years in prison.

The medical community has been protesting the government's increase of the medical school admissions quota to address the shortage of doctors in the country.

Trainee doctors have walked off the job since late February, and medical professors serving as senior doctors at Seoul National University hospitals began an indefinite walkout since Monday.

The KMA has threatened to hold an indefinite strike starting June 27 unless the government accepts its demands, including revisiting the quota hike decision. (Yonhap)