The U.S. has welcomed Prime Minister Shinzo Abe's declaration that Japan intends to join the Trans-Pacific Partnership trade talks, but noted that more work needs to be done to win Washington's approval.

"The United States welcomes Prime Minister Abe's important announcement formally expressing Japan's interest in joining the TPP negotiations," Deputy U.S. Trade Representative Demetrios Marantis said Friday.

"Since early last year, the United States has been engaged with Japan in bilateral TPP consultations on issues of concern with respect to the automotive and insurance sectors and other nontariff measures, (while) also conducting work regarding meeting the TPP's high standards," Marantis said.