Winston Peters claims the Government co-operated with Fiji's military regime when the SIS "raided" a New Zealand-based member of the Fiji Freedom and Democracy Movement last year.
The NZ First leader says the questioning of former Fiji Cabinet minister Rajesh Singh and the search of his Auckland home by Security Intelligence Service and police personnel took place after the Government received "fictitious" information about an assassination plot aimed at military leader Frank Bainimarama.
Mr Peters first made the allegations in Parliament on Tuesday but yesterday went further, claiming the "raid" in which Mr Singh's computer and a phone were seized was illegal and that the GCSB were involved in spying on Mr Singh and his associates.
Mr Peters asked Prime Minister John Key if the Government had made an arrangement with the Fijian regime to spy on Mr Singh and other members of the Fiji Democracy and Freedom movement living legally in New Zealand.