Radical students, demanding the release of a jailed leader, battled police with firebombs and clubs Wednesday and threatened to disrupt Olympic events.

About 200 students attacked police in a brief clash at Korea University after a rally to demand the release of Oh Young-shik, a top radical leader charged Tuesday with violating national security laws.Students pelted riot troopers with scores of firebombs, and some attacked with wooden clubs.

"Why are the Olympics being staged when democratic figures are behind bars?" students chanted. "Release imprisoned students."