The U.S. Agriculture Department and lawmakers have reasserted their calls on South Korea to open more of its market to U.S. beef imports.

Agriculture Department spokesman Keith Williams warned Friday that the free trade agreement with South Korea will not be ratified until Seoul opens its beef market in accordance with international standards.

Williams urged South Korea to take additional steps to ensure that its beef import standards are based on scientific evidence, recognizing the safety of U.S. beef.

South Korea Friday finished quarantine inspections of six-point-four tons of U.S. beef, the first U.S. shipment since December 2003. The U.S. beef is expected to hit domestic store shelves next week.

Legislators also joined in the call for a full resumption of U.S. beef imports. Republican senator from Iowa Chuck Grassley threatened that if South Korea continues to block or limit the import of U.S. beef for allegedly unscientific reasons, the U.S. Congress will not implement the bilateral free trade agreement.

Montana Senator Max Baucus has also threatened to withhold support for the trade deal until beef trade is resumed. An aide to Baucus called the return of U.S. beef to Seoul "a positive development," but urged South Korea to embrace international guidelines and accept both boned beef and meat from cows older than 30 months old.

South Korea permits imports of meat from cattle under 30 months old on the condition that parts deemed risky such as bones are not included.

South Korea banned U.S. beef imports in December 2003 after the United States reported its first outbreak of mad cow disease. The nation lifted its ban on U.S. beef last October, but all three shipments that had arrived after that point were rejected when bone fragments were found in individual packages.

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