Japan held out on joining China's planned development bank Tuesday as ministers in Tokyo cast skepticism over its governance on the final day for nations to sign up as founding members.

Japan remains cautious about the prospect of becoming part of the Asian Infrastructure Investment Bank and has yet to get answers from China on questions about the governance of the institution, Finance Minister Taro Aso told reporters.

The AIIB has the potential to weaken the clout of the almost 50-year-old Asian Development Bank, which is dominated by Japan and the U.S.