Leaders of the Korean Medical Association, the country's biggest doctors' group, appeared before police on Wednesday for another round of questioning over suspicions of instigating a mass walkout by trainee doctors.

Joo Soo-ho, the chief KMA spokesperson, and Park Myung-ha, the group's organization consolidation chief, arrived at the Seoul Metropolitan Police Agency's public crime investigation office in Seoul to undergo questioning.

Joo and Park are among the five former and current KMA leaders against whom the government has filed a police complaint, accusing them of instigating the mass walkout by trainee doctors. The collective action has continued for a month in protest against the government's plan to hike the medical school quota by 2,000 seats starting next year.

Before entering the police office, Joo threatened to launch a campaign for the ouster of the government of President Yoon Suk Yeol, accusing it of infringing upon the freedom of speech and assembly.

"Starting today, we will muster the support of 140,000 doctors to launch a campaign to oust the Yoon Suk Yeol administration," he said.

Joo said that the freedom of speech and assembly constitutes the very basic foundation of a free democracy, and he will take the lead in the campaign to safeguard free democracy.

Wednesday's questioning marks the second time and the fourth time that Joo and Park have undergone a police investigation in connection with the walkout. (Yonhap)