Fast-food chain operator Mos Food Services Inc. said Tuesday it will suspend sales of burgers made with U.S. beef after each shop's current inventory runs out, possibly beginning in February.

The decision concerns the Mos Rice Burger Yakiniku, priced at 300 yen, and follows a government decision last month to ban U.S. beef imports due to the case of mad cow disease there.

The burger is the most popular among three types in the Mos Rice Burger series.

American beef accounts for about 2 percent of all beef used by Mos Food Services.

The company said it is difficult to reproduce the Yakiniku Burger taste if beef from another country is used.

U.S. again says no

WASHINGTON (Kyodo) The United States cannot accept Japan's call that all slaughtered cattle be tested for mad cow disease because it is scientifically unjustified and too expensive, an Agriculture Department official said Monday.

The estimated cost of testing Japan-bound meat alone -- up to $900 million -- is equal to about 90 percent of annual U.S. beef exports to Japan, worth $1 billion, said David Hegwood, senior adviser to the agriculture secretary on international trade.

"So it's just not worth it economically to go down that road, nor is it justified scientifically," he said.