South Koreans' protests against the resumption of U.S. beef imports continued until early Sunday morning despite Washington's moves not to export beef from older cattle to South Korea.

Thousands of South Koreans scuffled with riot police in central Seoul until early Sunday morning as they tried to march toward the presidential office of Cheong Wa Dae to protest the U.S. beef import deal signed in mid-April.

About 40,000 protesters marched in downtown Seoul Saturday, the last day of the 72-day candlelight vigil, calling for complete renegotiation of the deal for a stricter age limit, and some of them continued their protests even after the end of the candlelight rally.

Some 8,800 protesters and thousands of police confronted violently at the Gwanghwamun intersection near the U.S. Embassy in Seoul, with many spraying fire extinguishers or hurling plastic water bottles at each other. Some demonstrators climbed onto the barricades of police buses demanding President Lee's resignation, Yonhap News reported.

About 10 people suffered facial and head injuries in the clashes and 11 people were arrested for violence.

President Lee Myung-bak called U.S. President George W. Bush Saturday night (Korean time) to ask for cooperation to ensure that U.S. beef from cattle older than 30 months, considered at greater risk of mad cow disease, is not exported to Korea, and Bush promised to do so, according to Lee's office.