Fiji's police chief said Tuesday his officers were investigating allegations of a plot to destabilise the government, refusing to deny it may have emanated from the force's own ranks.

Acting police commissioner Sitiveni Qiliho said the alleged plot was discovered when an Internet cafe owner found incriminating emails left open on one of his computers.

"He's supplied me with printouts that are pointing towards destabilising acts against the government... I cannot confirm or deny police involvement," Qiliho told the FijiVillage news website.

He said the cafe owner, named in Fijian media as Rajneel Singh, was in protective custody after alleging he was beaten by police in the western town of Lautoka, where he is based. Singh had initially alerted the police.

The front page of Tuesday's Fiji Sun carried a picture of a shirtless Singh, his face obscured, showing deep cuts and abrasions on his back.

"I am lucky to be alive," he told the newspaper, saying he discovered details of the plot when a computer user at his cafe failed to log off properly.

Qiliho did not provide details of the alleged conspiracy, simply saying investigations were continuing.

"But I want to assure the safety of the people," he told reporters.

Fiji has endured four coups since 1987, the most recent of which was carried out by the military in 2006 under the command of current Prime Minister Voreqe Bainimarama.

Some 70 people were arrested in August and charged with sedition, with Bainimarama accusing them of plotting to overthrow the government amid reports of plans to establish a breakaway state in the Pacific nation.