Japan's top government spokesman says Tokyo has no plan as of now to join the China-led Asian Infrastructure Investment Bank.

Chief Cabinet Secretary Yoshihide Suga told reporters Tuesday that Japan is still seeking answers about how the regional financing institution would be governed.

Beijing has set a March 31 deadline for founding members to express interest in joining the AIIB.

The U.S. maintains that the Beijing-based regional bank should work in partnership with existing institutions such as the World Bank. It contends the bank might extend credit without adequate environmental, labor and social safeguards.

But it has found itself isolated on the issue as other major Western countries have indicated they plan to join.

Suga denied reports Japan was seeking more time to decide on the issue.