A candidate backed by Japanese Prime Minister Shinzo Abe claimed victory in a mayoral election in Okinawa on Sunday, beating an opponent of a planned new US military base there.

The election was the latest episode in a long dispute about the future of the base, which has deepened mistrust between the central government and the southern island chain.

Incumbent Ginowan mayor Atsushi Sakima, 51, was certain to be re-elected with the support of Abe's ruling coalition to continue governing the island's main city, where the US Futenma air base is located, according to exit polls by major broadcasters.

The official result is expected early Monday.

Sakima edged out Keiichiro Shimura, 63, who was supported by Okinawa governor Takeshi Onaga.

Onaga has vowed to prevent the central government from constructing a new US Marine air base in a remote part of the island to replace the existing Futenma base in heavily populated Ginowan, where it is widely seen as a potential danger to residents.

Many island residents want a replacement for Futenma built outside Okinawa -- either elsewhere in Japan or overseas -- saying they can no longer live with the noise, accidents and occasional crimes by US service members.

Sakima also says moving Futenma is a top priority, but has stopped short of saying if he supports the central government's planned relocation elsewhere in Okinawa.

Sakima told NHK as he declared victory that he wants the base moved as soon as possible.

Asked where it should be relocated, he said only: "I'm not in a position to comment as it's supposed be decided by the Japanese and US governments."

The victory will offset disappointments for Abe in the past two local elections, won by anti-base politicians in the island.

The southern island chain and the central government have each sued each other as part of the long-running dispute.

Tokyo is keen to keep its crucial security ally the United States satisfied, but frustration over a seven-decade American military presence is rife in Okinawa.

The island accounts for less than one percent of Japan's total land area but hosts about 75 percent of US military facilities in the country.

Japan and the United States first proposed moving Futenma in 1996. But they both insist the base must remain in Okinawa -- from where US troops and aircraft can respond quickly to potential conflicts throughout Asia.