South Korean police on Saturday clashed with thousands of protesters, blocking their way to the presidential palace, where they hoped to demand a more vigorous government response to a ferry disaster that claimed more than 300 lives a year ago.

About 13,000 police and 470 police buses were deployed in the area around Seoul's main ceremonial thoroughfare and 100 protesters were arrested, an official of the Seoul Metropolitan Police Agency said.

Saturday's rally, organized by a group representing families of the victims, was the largest in recent weeks as the country marked the first anniversary of the April 16 disaster.