The Fiji-based Pacific Concerns Resource Centre says the free nature of the February by-election in French Polynesia in question as President Gaston Flosse is, as it put it, in a final scramble to hold on to his system.
The PCRC's spokesman, Peter Emberson, says therefore a transparent process is necessary involving international observers.
37 seats in the French Polyensian assembly are now empty after a Paris court found serious irregularities in the May general election which was organised by France.
Mr Flosse's rivals have called for the campaign and election to be followed by external monitors but Mr Flosse's party has said this is not necessary.
Mr Emberson says the Pacific Islands Forum, along with other international organisations, should take role in ensuring the elections are fair.
"French Polynesia is now an observer member of the Pacific Islands Forum and the Biketawa Declaration on governance and intervention has clear provisions for this. The Forum contineus to say that they need to be invited and that hasn't been done. The PCRC is asking them to exert influence and pressure."
Peter Emberson of the Pacific Concerns Resource Centre in Suva.