U.S. President George W. Bush on Wednesday urged Japan and South Korea to reopen their markets fully to U.S. beef exporters.

"When I'm talking to leaders, and they've got an issue with American beef, it's on the agenda," Bush told the National Cattlemen's Beef Association.

"I say, if you want to get the attention of the American people in a positive way, you open up your markets to U.S. beef," he added.

Japan and South Korea are major importers of American beef, but the two countries closed their markets after mad cow disease was discovered in the United States in 2003.