Japan and the United States have found "common ground" to forge a two-way trade deal, but may not be able to resolve remaining sticking points in time for a mid-May meeting of top negotiators seeking a broader regional deal, a senior Japanese official said.

Marathon talks during U.S. President Barack Obama's state visit to Tokyo last week yielded progress — hailed by the two sides as a "key milestone" — but the two stopped short of announcing a deal vital to the Trans-Pacific Partnership, a 12-nation bloc that will extend from Asia to Latin America.

The upbeat tone, however, was in contrast to the emphasis on "gaps" after previous rounds of talks on a bilateral deal that has been stalemated by differences over access to Japan's agriculture market and both countries' car markets.