The BBC Paris correspondent says the vote arose from a parliamentary initiative, and did not have the formal backing of the government.

According to some historians, up to a million and a quarter Armenians were massacred after 1915 as they were forced out of Turkey towards Syria by a government that feared they sympathised with Russia, at that time at war with Turkey.

Turkey, which recognises only that 300,000 people died, had already warned that such a vote would sour trade and diplomatic relations.

Some countries, Russia, Canada, and Turkey's regional rival Greece, have also deemed the slaughter a genocide, but France has now become the first major western European nation to do so.

It is a vote that correspondents say the French government would almost certainly have preferred not to have taken place.

Correspondents report that the French vote may further complicate relations between Turkey and the European Union, already strained over the EU decision to exclude it from membership, while inviting other countries - including Cyprus - to join.

In the past, the French government has shown itself more sympathetic to Turkish ambitions to join the European Union than some other states.

With a large Armenian community in France, the decision arose via a number of individual parliamentarians some of them with substantial Armenian presences in their constituencies.

A government minister has insisted that the vote referred to events that occurred during the Ottoman Empire and had no relevance to today's Turkey but it seems unlikely that Ankara will see matters in that light.