Japan's top court has finalized a ruling against Okinawa Prefecture over a landfill project for relocating a US military facility.

The Supreme Court on Thursday rejected an appeal by the prefecture challenging a decision of the central government. The court said the prefecture is not qualified to file the lawsuit.

The reclamation work off the Henoko district of Nago City is needed to move the US Futenma air station from a populated area in Ginowan City. The prefectural government revoked a permit for the work in 2018.

After Japan's land minister invalidated the move, the prefecture filed suit to overturn the decision.

Lower courts dismissed the case without passing judgment.

Justice Yamaguchi Atsushi said in Thursday's ruling that approving landfill and other projects is by nature an administrative task of the national government that has been legally delegated to prefectural authorities.

He said a prefectural government is not eligible to file a court case over the legality of a national government decision on such delegated affairs.

The central government's top spokesperson told reporters that the ruling backed the state's argument that Okinawa's appeal was unlawful.

Chief Cabinet Secretary Matsuno Hirokazu said the government will continue efforts to gain local understanding.

He also said the government will work to realize a full return of the air station at an early date, and eliminate the danger it poses to local people. He added that the base is called the most dangerous in the world.

Okinawa Governor Tamaki Denny said it is regrettable that the prefecture's appeal was dismissed on grounds of lack of legal qualification.

Tamaki said the prefecture will study the decision and consider what it can do to protect local autonomy.