Okinawa's governor has indicated he will not approve by Wednesday's deadline the Japanese government's project for the relocation of a US military base within the southwestern prefecture.

Tokyo plans to shift the US Marine Corps Futenma Air Station from the densely populated city of Ginowan to an offshore site at Henoko in Nago City.

But the ground of the site slated for reclamation was found to be too soft.

The central government then applied for permission from the prefecture to revise the plan and carry out reinforcement work. It has yet to approve the application.

Earlier this month, Japan's Supreme Court turned down Okinawa's appeal of a high court decision upholding the central government's directive for the prefecture to approve changes to the reclamation plan. Okinawa is now obligated to approve the project in line with the central government's instructions.

The minister of land and infrastructure had set September 27 as the deadline for Governor Tamaki Denny's approval.

Tamaki told reporters on Wednesday he needs to analyze various opinions from the people of Okinawa and scholars to ensure stable prefectural administration.

The land and infrastructure minister is expected to set a new deadline, and again instruct the prefecture to approve the project.

If the prefecture refuses to comply, the minister could file a lawsuit with the high court.

A win for the central government and refusal to comply by the prefecture again would mean Tokyo can issue an approval in what is called execution by proxy.