Fiji's military government has ordered Australia's top diplomat out of the country as a long-running dispute escalates. Sarah Roberts has been given 24 hours to leave the troubled South Pacific island nation.

Australia and Fiji have repeatedly clashed over the military's ousting of the South Pacific island's elected government in December 2006.

Canberra has criticized Fiji's failure to return to democracy and a series of repressive measures, including moves to muzzle the press.

The expulsion of Sarah Roberts, Australia's acting high commissioner to Fiji, escalates the dispute. Fiji's military leadership accuses Roberts of interfering in the country's internal affairs. Last November, Fiji also expelled Robert's predecessor.

Her expulsion comes after Australia lobbied for the postponement of a meeting of regional leaders, which was to have been held in Fiji later this month.

Australian Prime Minister Julia Gillard described Fiji's army rulers as behaving irresponsibly.

"Our attitude to this is we are gravely concerned that Fiji continues to take itself beyond and outside the workings of the international community. We will be making [it] very, very clear to Fiji our protest about this unreasonable and uncalled for action," Gillard said.

Australian officials say they have no plans to retaliate by ordering Fijian diplomats out of the country.

Fiji has already been suspended from the region's main political body, the Pacific Islands Forum, at the request of Australia and New Zealand.

The military chief, Commodore Frank Bainimarama, seized power in a coup three-and-a-half years ago. He accused the elected government of corruption and racism toward the country's ethnic Indian minority.

Commodore Bainimarama promised to cleanse the South Pacific nation of institutionalized racism and sleaze. After almost four years in power, democratic elections are likely to still be several years away, prompting concerns the army may want to hold onto to power indefinitely.  And Fiji's economy continues to slow, with the decline of key tourism and sugar cane industries.