There will be a delay in Japan's resumption of beef exports to the United States, halted when foot-and-mouth disease was found in Japanese cows, after Washington last week asked for details of Tokyo's food safety measures against domestic radioactive contamination, a farm ministry official said on Monday.

The United States originally targeted Aug. 17 to resume beef imports from Japan suspended in April 2010 after the discovery of Japanese cows infected with the virus.

"On Aug. 15, they asked us to hand in materials about food safety measures in the domestic market in the post-Fukushima period," the official said.

"But we understand their need to check, and we expect a few back-and-forth exchanges on this matter."

He gave no estimate of a new date for exports to resume.

The United States has set curbs generally in line with Japan's domestic measures on the import of other food products from Japan for fear of radioactive contamination since the Fukushima nuclear crisis sparked by last year's devastating earthquake and tsunami.

Japan's beef exports to the United States are almost negligible by comparison with U.S. beef imports by Japan, but the resumption could help farmers shift away from the domestic market, where meat prices have fallen, and increase corn imports from the world's biggest feed grain supplier.

Before the outbreak of the foot-and-mouth disease in Japan, beef exports totalled 565 tonnes in 2009, 72 tonnes of which was purchased by the United States, trade data show.

Japan is also reviewing its curbs on U.S. beef imports as global concern over mad cow disease ebbs.