The United States and Japan agreed in a joint statement on Friday that a key security treaty covers islands at the center of a territorial dispute between Japan and China, and said they would continue working toward a bilateral trade deal after talks failed to reach a conclusion.

In the statement, issued shortly before U.S. President Barack Obama left Japan after a state visit, the two nations said the Japan-U.S. security treaty covers the Japan-administered Senkaku Islands in East China Sea, expressing "strong concern" over tensions in territorial disputes between China and other Asian countries.

But the statement reaffirmed interest in building productive ties with Beijing.

The statement also said Japan and the United States are committed to bolder steps toward ambitious goals under 12-nation Trans-Pacific Partnership free trade talks. But they also admitted there is much work to be done before reaching a TPP agreement.

Obama and Prime Minister Shinzo Abe had ordered their top aides to make a final push to reach a trade agreement but Economy Minister Akira Amari told reporters on Friday morning that gaps remained despite recent progress.