South Korea's political opposition asked the Constitutional Court on Friday to block U.S. beef from entering the country after the government announced it would resume imports within days under an accord with Washington.

The government's announcement came despite widespread public opposition to the beef deal, which critics say fails to adequately protect against mad cow disease. About 9,000 people took to the streets in Seoul on Thursday night to denounce the move.

Three main opposition parties filed lawsuits Friday asking the Constitutional Court to rule that the government's move violates the people's right to health, and to issue an injunction against a resumption of imports until it issues a verdict.

They also demanded that all Cabinet members resign.

Constitutional Court spokesman Judge Kim Bok-ki said the court will deliberate the case expeditiously, but he did not give a timeframe.

Quarantine inspections of American beef shipments are expected to begin next week.

Still, U.S. beef is not expected to become widely available immediately because four major discount chains say they have no plans to put it on their shelves because of negative public perceptions of American beef.

"We cannot ignore public sentiment," said Na Geun-tae, an official with Lotte Mart, a major chain.

Friday night, about 2,500 people held a candlelight rally in central Seoul to urge the government to reverse the decision.

Earlier in the day, about two dozen members of a farmers' association held a protest in front of the presidential Blue House demanding the government reverse its decision to resume imports. All were marched into a police bus and taken away for questioning.

American beef has been the hottest issue in South Korea for nearly a month. Hardly a day has passed without the topic making front-page headlines or protesters holding candlelit vigils and street rallies in downtown Seoul against the agreement.

Protesters claim the government has ignored their worries about the safety of U.S. beef and accuse President Lee Myung-bak, who took office just three months ago, of making too many concessions to Washington to win U.S. congressional approval of the free trade agreement.

More than 200 protesters have been arrested in recent days, although many were subsequently released.

South Korea suspended imports after the first U.S. case of mad cow disease appeared in December 2003 in a Canadian-born cow in Washington state. Two subsequent cases were also discovered in the U.S.

Before the ban, South Korea was the third-largest overseas market for U.S. beef. A previous deal last year allowed restricted imports to reach South Korean consumers, but was quickly suspended after banned substances were found in several shipments.

Scientists believe mad cow disease, or bovine spongiform encephalopathy, spreads when farmers feed cattle recycled meat and bones from infected animals. The U.S. banned recycled feeds in 1997.

In humans, eating meat products contaminated with the cattle disease is linked to variant Creutzfeldt-Jakob disease, a rare and fatal malady.