France on Wednesday accused Turkey of "military involvement" on the side of Azerbaijan in its conflict with Armenia over the breakaway Nagorno-Karabakh region.
"The new aspect is that there is military involvement by Turkey which risks fuelling the internationalisation of the conflict," French Foreign Minister Jean-Yves Le Drian told parliament.
Armenia and Azerbaijan, two former Soviet republics, have for decades been locked in a conflict over Nagorno-Karabakh, an ethnically Armenian area which broke away from Azerbaijan in a 1990s war that cost about 30,000 lives.
Heavy fighting erupted again on September 27.
Both sides blame the other for starting the latest hostilities.
The conflict has drawn in regional players, with Turkey supporting Azerbaijan and Armenia hoping that its ally Russia, which has so far stayed on the sidelines, will step in.
Turkey has been accused of deploying fighters from Syria to support Azerbaijan in the fighting.
French President Emmanuel Macron recently claimed Ankara had sent Syrian "jihadists" to the region, accusing Turkey of crossing a "red line".
Turkey has not responded publicly.
Le Drian on Wednesday said France deplored "a large number of civilian casualties for little territorial progress on the part of Azerbaijan, given it is Azerbaijan that initiated the conflict."
He repeated the call for an immediate end to the fighting and a return to negotiations "without conditions" under mediation by the so-called Minsk group co-chaired by France, Russia and the United States.
"There will be meetings tomorrow in Geneva, other Mondays in Moscow and we hope that this will lead to the opening of negotiations," the minister said.