TOKYO (AFP) - Okinawan officials on Friday approved the long-stalled relocation of a controversial US military base, the defence ministry said, a breakthrough that looks set to remove a decades-long source of friction between Tokyo and Washington.

Local bureaucrats signed a document that gives the greenlight to a landfill, paving the way for the construction of a new base on the coast.

The defence ministry's Okinawa bureau confirmed that it received the document, which bore the governor's seal, from local government officials.

"The office received the document at 10:50 am (9:50 am Singapore time). It was approved," said an official of the ministry's branch office on Okinawa.

After years of staunch opposition, Okinawa governor Hirokazu Nakaima this week met Prime Minister Shinzo Abe, who pledged a big cash injection into Okinawa's economy every year until 2021.

Nakaima's nod marks a breakthrough on an original 1996 agreement to shut the Futenma airbase, which is in a densely-populated urban area.

The United States reaffirmed in 2006 it would re-site the base on the coast, but the move has been stymied by opposition throughout Okinawa, which feels overburdened by its outsized share of the American military presence in Japan.

The governor is expected to hold a press conference on Okinawa and announce his decision on Friday afternoon.