New Caledonia's pro-independence Caledonian Union says it will write to the French prime minister to express its surprise that thousands of indigenous Kanak people are missing from the roll of those elIgible to vote in the independence referendum.
The prime minister, Manuel Valls, is due in New Caledonia this week amid political tension and economic uncertainty.
The electoral rolls are highly contentious on a political level while the fall in the price of nickel has shaken the entire sector.
The Caledonian Union's president, Daniel Goa, has told Noumea's daily newspaper that the party doesn't find it normal that 21,000 people have not automatically been put on the list.
A vote is due by 2018 as the conclusion of the 1998 Noumea Accord, which is the territory's decolonisation roadmap.
The roll for the vote is being finalised based on terms which restrict voting rights to long-term residents.
Mr Goa sais a big challenge for his camp would be to mobilise those who habitually abstained from voting, suggesting they number about 46,000 people.