Japan's government has begun procedures to seek competitive bids for a land reclamation project off the coast of Okinawa Prefecture. The project is part of a plan to relocate a US military facility in the prefecture.

The government started the reclamation in 2018 to move the Futenma Air Station in Ginowan City in Okinawa to the less-populated Henoko district in Nago City, also in the prefecture.

As work progressed, it was found that a northern part of the reclamation site in Ooura Bay has soft ground and soil improvement work is needed.

The central government sought a design change to the original plan. But the prefecture refused to approve the revision, which halted the reclamation work.

Last year, the land ministry issued a directive demanding that the Okinawa government approve the design revision. This prompted the prefecture to file a suit seeking the withdrawal of the ministry's directive, arguing that the ministry's move was illegal.

On Monday, the Supreme Court upheld a high court ruling that said the state's directive was legitimate, and rejected Okinawa's appeal.

The ruling paved the way for the work to resume as it obliges the Okinawa government to give its approval.

On Friday, the Okinawa Defense Bureau began procedures to select contractors through competitive bidding for four projects, of which three include work to solidify the soft ground in Ooura Bay.

The Defense Ministry says about 71,000 piles are needed to be driven into the seabed.

The ministry estimates it will take about 12 years to complete the construction of the new facility based on the revised plan.

The Okinawa prefectural government insists that the planned soil improvement work in the bay is an unprecedented, large-scale and sophisticated project, but its design is not sufficiently safe.