Two U.S. Senators have urged Japan not to impose emergency tariffs on beef imports from the United States and other countries.

Charles Grassley, an Iowa Republican and chairman of the Senate Finance Committee, and Max Baucus, a Montana Democrat, made the request in a letter sent Thursday to Japanese Ambassador to the U.S. Ryozo Kato.

The U.S. lawmakers said the imposition of a safeguard measure on beef imports to Japan threatens to disrupt trade in beef.

"To impose this mechanism would harm U.S. beef producers as well as a wide range of Japanese consumers," the letter said.

Japan, the biggest market for U.S. beef producers, bought more than $1.2 billion worth of U.S. beef in 2001.

Under a World Trade Organization agreement concluded in the Uruguay Round of multilateral trade talks, Japan can automatically increase the tariff on beef from 38.5 percent to 50 percent if there is an increase of more than 17 percent in beef imports in a three-month period from the previous year.

There is a growing possibility that Japan may levy additional tariffs this summer.

Grassley and Baucus argued that the recent growth in beef imports to Japan simply represents a recovery in the market following an outbreak of mad cow disease in Japan in September 2001.