SUVA (AFP) - Fiji's acting president Ratu Epeli Nailatikau was sworn in as head of state of the military-ruled Pacific nation Thursday.

Nailatikau, a former army commander credited with guiding self-appointed Prime Minister Voreqe Bainimarama through his military career, was appointed as acting president after Ratu Josefa Iloilo retired at the end of July.

President Nailatikau had been appointed vice president in April, a week after Bainimarama repealed the constitution, sacked the judiciary and introduced emergency regulations including press censorship.

The largely ceremonial positions of president and vice president were traditionally appointed by Fiji's Great Council of Chiefs, sidelined by Bainimarama soon after he ousted the elected government in a 2006 coup.

Nailatikau was sworn in by Chief Justice Anthony Gates at Government House in the capital Suva in a ceremony attended by military officers, government officials and some diplomats.

Australia and New Zealand were not represented after Bainimarama on Tuesday expelled their top envoys over travel sanctions against Fiji's judiciary.

Wellington and Canberra Wednesday expelled the Fijian mission heads in a tit-for-tat retaliation.

An Australian academic was ordered out of Fiji by the military regime Thursday, a day after he was arrested for giving media interviews on the political situation in the country.

Brij Lal, an expert on Fiji politics at Canberra's Australian National University, left Fiji for Sydney Thursday morning.

Lal, a regular visitor to Fiji, was arrested as the nation expelled the envoys of Australia and New Zealand, triggering tit-for-tat expulsions from Wellington and Canberra.

"I was in a cell for an hour and interrogated and told to leave the country within 24 hours or else," Lal told Australia's ABC Radio late Wednesday.

Lal said it was the first time he had been arrested by the Fijian military, which ousted the elected government in a December, 2006 coup and was involved in three other coups in the past two decades.

"This tells you something about the state of Fiji at the moment," he said, adding there was no freedom of speech.

Lal said he saw no end in sight to Voreqe Bainimarama's rule, adding the military was effectively in control of the public service, the bureaucracy and the judiciary.

"If and when elections are held they'll be held in such a way as to ensure the military remains in power," he said.