With American beef now trickling back into Japan following a two-year hiatus, U.S. officials and Japanese beef importers are calling on Tokyo to relax its stringent regulations further. But the immediate problem is convincing a public concerned about mad cow disease to eat the beef that is allowed in.

With knives in hand, U.S. Ambassador Thomas Schieffer and Philip Seng, president of the U.S. Meat Export Federation, were given the cue to carve Wednesday at a banquet in a top Tokyo hotel. Before an audience of Japanese meat industry executives and news photographers, Ambassador Schieffer and Mr. Seng carved a roast beef that had been air-freighted to Japan.

, a Japanese citizen who plays in the United States for the champion Chicago White Sox baseball team, was on hand as a celebrity guest. The carefully staged event was meant to whet the appetites of the Japanese public for American beef.

Ambassador Schieffer told reporters that the resumption of imports is merely the first step. "It does no one any good just to have the government lift the ban," he said. "What we want to do is go into the marketplace now and persuade each Japanese household that this is a safe product, because we know that they like it."

Recent surveys have shown that the majority of Japanese are reluctant to eat American beef, after one cow was found in Washington State in 2003 with the brain-wasting disease bovine spongiform encephalopathy, or BSE.

Before that incident, Japan was America's largest beef export market, with shipments totaling nearly one-and-a-half billion dollars annually. After the BSE discovery, the Japanese government banned all beef imports from the United States.

Mr. Schieffer is calling on Japan to relax its restrictions on beef imports further. Those restrictions are now the most stringent in the world, banning meat from any cattle older than 20 months.

"Japan is the only place that puts a prohibition on beef that is in the 21-to-30-month period," he said. "And we would ask the Japanese to look at that and to try to bring their standards more in conformity with the rest of the world."

The United States has asked for the limit to be raised to 30 months. Younger animals usually have not yet developed the flavorful fat, known as marbling, that is preferred by many Japanese - and many Americans.

But the theory is that by 20 months of age, animals have also not yet had time to develop BSE.

U.S. agricultural officials are due to hold talks with their South Korean counterparts in mid-January to discuss the end of a ban on U.S. beef imports there. Before December 2003, South Korea was the number-three export market for U.S. beef.