U.S. beef exports to Japan are to resume soon under an agreement reached yesterday to ease a 10-month ban on the meat prompted by a case of mad cow disease in Washington state.

Japan is to allow beef imports from cattle younger than 20 months, U.S. Agriculture Undersecretary J.B. Penn said in Tokyo after three days of negotiations. Full beef trade may resume after a review in July, he said. U.S. officials are going to South Korea and Taiwan today for negotiations on reopening those markets.

Japan, the biggest overseas customer for U.S. beef, and more than 40 other nations suspended imports of the meat in December 2003 after the government announced the first case of mad cow disease in U.S. history. The import bans threatened more than $3.8 billion in annual U.S. exports and eroded profit for beef producers such as Tyson Foods Inc. and Cargill Inc.

"This agreement is kind of the gateway to all the other markets that haven't opened yet," said Gregg Doud, an economist with the National Cattlemen's Beef Association. He said he expects South Korea, which bought more than $500 million worth of U.S. beef in 2003, to resume purchases after Japanese shipments resume. "The Koreans have signaled for some time that they were waiting on the U.S. and Japan," Doud said.

Japan bought more than $1.7 billion worth of U.S. beef and beef products in 2003, according to a statement yesterday from the Agriculture Department. The U.S. Meat Export Federation put the figure at $1.5 billion.

Mexico, the second-biggest buyer of the meat, had been the only major U.S. trading partner to resume purchases since the case of bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, surfaced in Washington in December. Korea is the third-biggest overseas customer for U.S. beef. Taiwan is the sixth-largest.

"We're talking here a matter of weeks" before Japan begins importing some U.S. beef, Penn said. "We are very eager to once again be able supply high-quality, safe beef products to Japanese consumers."

Beef trade may expand after procedures for confirming the age of cattle that qualify for import are reviewed with participation from U.S., Japanese, World Health Organization and other experts in July, Penn said.

Under the agreement, Japan would also be allowed to resume exporting beef to the United States from cattle under 20 months old. The United States banned beef from Japan after that country found the first of more than a dozen cases of BSE in September 2001. Japan had been shipping 70 to 100 tons of beef a year, mostly premium Kobe beef, to the United States.

Exports account for about 10 percent of total U.S. beef production. Tyson Foods of Springdale, Ark., is the biggest shipper, followed by Cargill of Wayzata, Minn.

Taiwan is also expected to reopen its markets shortly, said Lynn Heinze, a spokesman for the U.S. Meat Export Federation. Taiwanese officials completed a review of U.S. safety standards last week and expects to host a technical team from the United States in the next few weeks, he said. "Taiwan looks pretty good," Heinze said.