U.S. Trade Representative Robert Lighthizer urged Japan on Wednesday to make "unilateral concessions" on beef imports to help reduce its trade surplus with the United States.

"I think in the areas like beef and the others, they ought to make some unilateral concessions — at least temporary concessions," Lighthizer said at a hearing at the Senate Committee on Finance, prodding the world's third-largest economy to further open its beef market.

"And I don't quite understand why that doesn't happen," he said. "That's a simple way to get that trade deficit down and doesn't cost them anything."