Finance Minister Taro Aso on Friday sounded a cautious note about the potential benefits of striking a bilateral trade deal with the United States, saying it would not necessarily give Washington better terms than the multilateral Trans-Pacific Partnership accord, from which it recently withdrew.

"There is no guarantee that the United States can get better conditions on a bilateral basis than under the TPP," Aso told a news conference after the conclusion of a meeting of Group of 20 finance chiefs in Washington.

"We believe the TPP is a good system for the United States and Japan," Aso said, expressing his view that both countries need to discuss what would be best for them.