The deal came after weeks of mass protests in Seoul by Koreans who believe the older cattle are more likely to carry mad cow disease and who demanded the South Korean government reverse an unpopular decision to lift a former ban on such beef. The new deal will involve the introduction of a cow age verification system, Yonhap, the South Korean news agency, reported Saturday.

The agreement was reached between South Korean Trade Minister Kim Jong-hoon and U.S. Trade Representative Susan Schwab, Yonhap said. Officials said the new age-verification system will ensure that only allow beef from cattle less than 30 months of age to be exported into South Korea.

"The age-verification system will be in place until concerns over safety of U.S. beef subside," Kim said in a briefing for reporters.

Yonhap said the agreement came after U.S. beef industry said Friday it was willing to limit Korean exports to cattle less than 30 months of age under a program verified by the U.S. government.