Thousands of South Koreans took to the streets in central Seoul again Friday, as the country's trade minister headed to Washington for talks to ease their fears over U.S. beef imports.

Kim Jong-hoon will meet with U.S. Trade Representative Susan Schwab to press for additional safeguards against the supposed dangers of mad cow disease. Seoul's decision last month to resume imports of U.S. beef sparked mass protests, and South Korea's Cabinet's has offered to resign in response.

Kim is expected to seek a revision of the agreement to exclude imports of U.S. beef from cattle older than 30 months, which is potentially more at risk from the disease. The U.S. says its beef has been proven to be perfectly safe.

South Korea stopped U.S. beef imports in 2003 after a single case of mad cow disease was detected in the United States.

South Korea's imports of beef from U.S. cattle 30 months old or younger, which is considered safer, began last year.

The beef issue has become a touchstone for a host of other grievances against South Korean President Lee Myung-bak, who has held office less than four months. Prime Minister Han Seung-soo and the entire Cabinet offered to resign Tuesday to take responsibility for the crisis.

U.S. lawmakers had made it clear they would not approve a free trade agreement with South Korea unless Seoul agreed to lift restrictions on beef imports.

Thousands of protesters have rallied almost nightly for about a month to protest the beef agreement. Some groups today also protested against what they call unfavorable deals imposed on South Korea by the United States.

Anti-U.S. protests today also included activists marking the sixth anniversary of the accidental death of two Korean girls involving a U.S. military vehicle in Ynagju, Gyeonggi province.

Some information for this report was provided by AFP, AP and Reuters.