Japan and the United States remained divided Friday over Tokyo's ban on U.S. beef imports, but agreed to continue discussions on the matter Saturday.

The extension of the two-day talks, which were initially expected to finish Friday, indicates that there is still a gap between the two sides on the scientific methods used to determine a cow's age.

"The negotiations did not break down . . . we will continue talks," a senior Japanese official said.

During the talks, Japan explained that the state-appointed Food Safety Commission is examining whether to exempt cows aged 20 months or younger from testing for bovine spongiform encephalopathy.

The U.S. side, represented by U.S. Agriculture Undersecretary J.B. Penn, claimed that it is able to establish an animal's age by checking the quality of its meat and the formation of cartilage, but Japan has dismissed this method, sources said.

Washington also said it can verify a cow's age because farms keep track of herds of cows born in similar time periods, the sources said.

However, Japan demanded stricter measures, such as tagging the cow with its birth date and location.

The U.S. also said that Japan's BSE testing for cows aged 20 months or younger should be a temporary measure, urging it to review its policy after a certain time frame, the sources said.