Tokyo, Feb 24 (IANS): Voting was underway on Sunday in a referendum on the relocation of US military base in Japan's Okinawa prefecture.

Okinawa Governor Denny Tamaki hoped that the referendum, which is not legally binding, would show opposition on the part of the local electorate to the relocation of the US Marine Corps Futenma air station to the Henoko Bay from a residential area, reports Efe news.

The land reclamation work, on in the Henoko Bay, has been opposed over potential damage to environment.

The voters must choose one of three options to say if they support, oppose, or neither support nor oppose the relocation of the air base.

Around 1.15 million Okinawa residents, over the age of 18, are eligible to cast vote. Counting is set to begin immediately after polling stations close at 8 p.m.

Tokyo and Washington signed an agreement in 1996 to relocate the base following a controversy, triggered by rape of a 12-year-old Japanese girl by three US soldiers.

The Okinawa authorities, however, moved court to stall the project despite Japan's Supreme Court ruling in favour of the relocation in 2016.

Approximately one fifth of the main island of Okinawa forms part of the US military base. It houses more than half of the nearly 47,000 troops that the US maintains in Japan, as well as 74 per cent of military facilities in Japan.