New Caledonia's pro-independence leader Roch Wamytan says the territory should have remained an associate member of the Pacific Islands Forum because it is not an independent country.
Last month's Forum leaders summit admitted New Caledonia and French Polynesia as the first and only members inscribed on the United Nations decolonisation list.
In an interview on local television, Mr Wamytan says New Caledonia has been used like a Trojan horse by France to get into the Forum which had been set up as a body of independent countries.
He said being New Caledonian he defends New Caledonia's interests, yet a situation can arise where New Caledonia's leaders will have to defend the interests of France which has the regal powers in the territory.
Paris had been pushing for its Pacific territories to become Forum members since 2003 and last month they were admitted with the explicit support of New Zealand and Australia.
The access criteria for full Forum membership remain unclear.
The Pacific Islands Forum website said the group is made up of independent and self-governing states.