The Japanese government agreed Wednesday to lift the ban, pending thorough inspections of U.S. meat- processing facilities.

But the Democratic Party of Japan and three smaller opposition parties released a statement Saturday criticizing the resumption, saying it could put Japanese consumers at risk.

"To secure food safety for our citizens, the resumption of U.S. beef imports should not go ahead at this stage," the statement said. Japanese consumer groups have also opposed resuming the imports.

The parties also demanded a meeting with Prime Minister Junichiro Koizumi but the premier rebuffed the request, saying he was busy preparing for his trip to Washington next week, according to Kyodo News agency.

Japan's ban, first imposed in 2003 over concerns that U.S. beef might be infected with mad cow disease, was lifted at the end of last year.

Japan again halted the imports in January after a shipment was found to contain prohibited parts of cows considered by Tokyo to be at risk of the disease.

Mad cow disease is formally known as bovine spongiform encephalopathy, or BSE. In humans, eating meat contaminated with BSE is linked to variant Creutzfeldt-Jakob Disease, a rare and deadly nerve disease.

Japanese inspectors plan to tour 35 U.S. meatpacking plants to ensure the facilities comply with Japanese import regulations before allowing American beef back into Japan.

A group of U.S. senators has proposed legislation that contains a nonbinding call for trade sanctions unless the imports are restarted by the end of the summer.

Koizumi is scheduled to meet U.S. President George W. Bush in Washington on June 29.