Voters in the South Pacific archipelago of New Caledonia overwhelmingly chose to remain French on Sunday but turnout was poor following a pro-independence boycott.
Pro-independence parties said on Monday that they "do not recognise the legitimacy and validity of this ballot which has been confiscated from them".
Voters were asked to vote yes or no on the question: “Do you want New Caledonia to achieve full sovereignty and become independent?”
With three-quarters of the vote counted, 91% of those who took part chose to stay in France, according to regional officials.
The overall turnout was just 41% — less than half the numbers who showed up in a previous independence referendum last year, where support for breaking away was 46.7%.
The vote is part of a decades-long process of decolonisation but pro-independence forces had refused to take part after an effort to delay the vote in part due to the COVID-19 crisis failed.
French President Emmanuel Macron hailed the result, tweeting: "The Caledonians have made the choice of France, that of unity, that of confidence. I am very proud of it. It is now up to us to continue to build this common destiny that our elders dreamed of and initiated."
The archipelago became French in 1853 under Emperor Napoleon III and was used as a prison colony.
But the territory of 270,000 people won broad autonomy after violence in 1988 led to a political process known as the Noumea Agreement.
The accord provides for the "progressive, accompanied and irreversible transfer of powers from the French state to New Caledonia" except for powers over defence, security justice, foreign affairs and currency.
In the first such referendum in 2018, 43.6% of voters supported independence, and 46.7% supported it in the second vote in 2020.
Pro-independence parties, which came together under the "Strategic Independence Committee for Non-Participation" banner, said in a statement that they do not recognise the "legitimacy of the referendum" as it was "not in conformity with the spirit and the letter of the Nouméa Agreement, a decolonisation process, and not in conformity with the UN resolutions which included New Caledonia n the list of countries to be decolonised."
They said "the NO vote declined in all polling stations" and that "the anti-independence electorate was eroded by 7397 votes compared to the 4 October 2020 vote" despite the boycott.
"The path of dialogue was thus broken by the stubbornness of a French government unable to reconcile its geostrategic interests in the Pacific with its obligation to decolonise our country," they added.
"Emmanuel Macron's speech to "validate" the results does not do credit to France. Everyone must now draw the consequences," they added.
The vote comes as France works to maintain its presence in the region following the AUKUS deal in September that ended a French submarine contract with Australia.
New Caledonia hosts one of two French military bases in the Pacific, which allows France to contribute to regional security.