The Fijian Political Party, the SVT, says a break-in at its Suva office on Sunday night was politically motivated.
The Fiji Times quotes the SVT spokesperson, Ema Druavesi, as saying the only things missing were files and the intruders did not take computers and other equipment.
Ms Druavesi says the thieves opened a safe and targetted only the files inside, which included applications from those who had applied for SVT tickets to stand in the May general election.
She says the SVT has asked those who had applied for party endorsement to re-apply.
Meanwhile, the SVT leader, Sitiveni Rabuka, is in India for knee surgery.
An Indian news agency, the Amedabad Newsline, says Mr Rabuka has told a news conference there that his 1987 coups were democratically wrong.