The people on the Indian Ocean island of Mayotte have voted overwhelmingly in favour of it becoming an integral part of France.
The French Interior Ministry said the vote was more than 95% in favour.
The result had been widely predicted, with supporters of the move pointing out the economic gains available.
The referendum has caused controversy in the region, because the Comoros have always laid claim to Mayotte, which the African Union considers part of Africa.
The Comoran vice-president said the vote was a declaration of war.
Geographically, Mayotte is part of the Comoros archipelago, but in the 1970s it voted to remain tied to France as part of an "overseas collectivity".
While many African countries were fighting for independence, the people of Mayotte resisted separation from France.
And when the three other islands in the Comoros archipelago became independent in 1975, Mayotte remained part of France.
The Comoros islands probably hold the world record for coups, says BBC Africa analyst Mary Harper.
There have been more than 20 coups and secession attempts since independence, while Mayotte has remained stable.
It also has a much stronger economy, with a GDP about 10 times higher than that of the Comoros.
Despite Mayotte's close ties with France, it would be wrong to see this tiny island of fewer than 200,000 people as a sort of mini-France, our correspondent says.
Although French is the official language, only about 50% of the population can read or write it.
It is a predominantly Muslim country, where polygamy is practised and girls can marry at the age of 15.