SEOUL, South Korea (AP) -- Thousands of protesters marched through Seoul against a U.S. beef import pact that has renewed fears of mad cow disease. Police said Tuesday that 30 demonstrators were arrested after scuffling erupted.
A crowd estimated by police at 3,000 held a candlelight vigil Monday night before embarking on the march.
''Nullify the agreement,'' the protesters chanted as they were stopped by some of the 7,000 riot police blocking off streets downtown.
The rally ended in the early hours Tuesday as police dispersed the protesters, leading to clashes but no serious injuries, officials said.
Twenty-nine protesters were detained, according to a police official, who spoke on condition of anonymity because he was not authorized to talk with media.
The latest arrests came hours after police freed 36 out of 68 demonstrators detained at separate rallies over the issue Sunday. Police plan to decide how to handle 32 others by later Tuesday.
Thousands of South Koreans, mostly students and other young people, have held similar vigils and street rallies on a near daily basis against the April 18 deal to resume U.S. beef imports.
The protests are one of the biggest domestic challenges faced so far by South Korean President Lee Myung-bak, who took office three months ago. Lee last week sought to reassure the country over the safety of U.S. beef, but failed to ease public anger, which has been fanned by media reports questioning the safety of U.S. beef.
Lee, who was scheduled to depart Tuesday for a visit to China, has been criticized for making too many concessions on the beef issue to prompt the U.S. Congress to approve a free trade agreement. South Korea and the U.S. agreed to the landmark accord last year to slash tariffs and other trade barriers, but the deal must still be endorsed by legislatures in both countries.
South Korea suspended U.S. beef imports after the first American case of mad cow disease appeared in December 2003 in a Canadian-born cow in Washington state. A total of three cases of the disease have been discovered in the United States.
After protracted negotiations, restricted imports of U.S. beef reached South Korean supermarkets last year, but further shipments were canceled in October after banned parts, such as bones, were found.
The new beef agreement scrapped nearly all the quarantine restrictions imposed by the previous government to guard against mad cow disease.
Scientists believe mad cow disease, or bovine spongiform encephalopathy, spreads when farmers feed cattle with recycled meat and bones from infected animals. In humans, Creutzfeldt-Jakob disease, a rare and fatal malady, is linked to eating meat products contaminated with the cattle disease.