A former Japanese minister has warned domestic terrorists could strike Tokyo if the government fails to address anger in Okinawa over a heavy US military presence there.

Shozaburo Jimi, minister in charge of financial services and postal reform, under the last government, suggested Wednesday that residents of the sub-tropical island chain may also push for secession from Japan.

"Okinawa has long had a history of independence movements and movements for self-governance. I hope those things will not blaze up," he told local media.

"There's a possibility that (Okinawa) will say it will become an independent state," Jimi said, according to Kyodo News.

"Domestic guerrilla (struggles) could occur as a result of separatist movements," and "terrorist bombings could occur in Tokyo, depending on how the state handles" the issue, said Jimi.

The comments came as Prime Minister Shinzo Abe, who swept to power in a December election, reiterated his policy of strengthening the Japan-US military alliance and said he was pushing ahead with an unpopular plan to move a large US air base within the prefecture.

Jimi's statements, which come ahead of Abe's weekend visit to Okinawa, were seen as an attempt to press the government to ease the burden on the southern Japanese prefecture, reluctant host to more than half of the 47,000 US military personnel in Japan.

Despite calls from local Okinawan politicians, the central government has stood firm on its plan to move the Futenma Air Station from a residential district of Okinawa to a sparsely populated shoreline area.

Domestic terror attacks hit Japan in the 1960s and 1970s during huge social upheaval and as part of a radicalist and student movement, but the country has since largely escaped the blight of organised political violence.

Jimi is head of the small People's New Party, which was part of the ruling bloc until a December election saw it routed, including in Okinawa.

The often-fractious relationship between the US military and the communities that host them has been further irritated in recent months by a series of crimes committed by drunken servicemen, including the gang rape of a local woman.

Opponents have also seized on the deployment to Okinawa of tilt-rotor Osprey aircraft, which they say have a questionable safety record and put people living nearby at unnecessary risk.