Tokyo ? Japan hopes the United States will not impose economic sanctions over Tokyo’s 15-month ban on American beef and will continue negotiations, the government’s top spokesman said Wednesday.

Some members of the U.S. Congress have warned of possible sanctions if Japan does not lift the ban soon.

“We are working hard to understand each other’s positions better and solve the problem,” Chief Cabinet Secretary Hiroyuki Hosoda said. “We hope that the U.S. side will take note of discussions on the Japanese side.”

The ban was imposed in December 2003 after the United States discovered its first case of fatal brain-wasting mad cow disease, formally known as bovine spongiform encephal-opathy.

Before the ban, Japan was the most lucrative overseas market for U.S. beef producers, buying $1.7 billion worth of beef in 2003.

Japan tentatively agreed in October to resume imports of beef products from young cows considered less at risk for the disease, but discussions stalled over how to authenticate the age of cattle.

Earlier this month, a Japanese government panel took a step toward partially lifting the ban by recommending that Japan begin importing U.S. grade A40 beef, which comes primarily from cattle 12 to 17 months old.

But a final decision still has to be approved by the Food Safety Commission and then the agriculture and health ministries.

Public broadcaster NHK reported that persistent concerns from Japanese consumer groups about U.S. beef safety was prolonging the commission’s proceedings.