The French parliament is due to vote on a law that would make it a crime to deny that Turkey perpetrated a genocide against Armenians in 1915-17.
The French bill has brought strong protests in Turkey
Turkey says the law could seriously damage bilateral relations and French businesses fear a trade backlash.
Armenians say Ottoman Turks killed 1.5m of their people in a systematic massacre. Turkey strongly denied this.
The law would establish a one-year prison term and 45,000-euro ($56,400) fine for those denying genocide.
Turkey has been warning France for weeks not to pass the bill.
Turkish Foreign Minister Abdullah Gul said on Wednesday: "If this bill is passed, Turkey will not lose anything but France will lose Turkey. [France] will turn into a country that jails people who express their views."
The vote, in the lower house of the French parliament on Thursday morning, has been sponsored by the opposition Socialist party.
The ruling Union for a Popular Movement (UMP) is not backing the law, but has given its deputies a free vote, and analysts say it is likely to pass.
The law would still need the backing of the upper house and President Jacques Chirac, but French businesses are already fearing a backlash in trade with Turkey.
EU enlargement commissioner Olli Rehn said the bill was "counterproductive".
EU membership bid
The BBC's Sarah Rainsford in Istanbul says many Turks are angry at what they see as double standards in the EU, where opinions are sharply divided about Turkey's membership bid.
The official Turkish position states that many Christian Armenians and Muslim Turks died in fighting during World War I - but that there was no genocide.
France's President Chirac and Interior Minister Nicolas Sarkozy have both said Turkey will have to change that position and recognise the Armenian deaths as genocide before it joins the EU.
Turks argue that while the EU is pressuring Turkey to improve its legislation to ensure full freedom of speech France seems to be moving in the opposite direction.
Arguments have raged for decades about the Armenian deaths
Turkey's parliament is now considering a law that would make it a crime to deny French killings in Algeria in 1945 as genocide.
But Prime Minister Recep Tayyip Erdogan objected, saying: "We are not like those who clean dirt with dirt."
France has about 500,000 people of Armenian descent - thought to be the largest Armenian immigrant community in western Europe.
There are accusations in Turkey that the Armenian diaspora and opponents of Turkey's EU membership bid are using this issue to prevent Turkey joining the 25-member bloc.
The Socialist MP and former minister Jack Lang helped to draft an existing French law which recognises that Armenians suffered genocide in Turkey.
But he told the BBC's World Today programme that the new bill was unnecessary.
"I cannot give my vote to a completely stupid law which will punish somebody who expressed free judgement concerning historical facts. It's not acceptable.
"We have to help Turkey to accept, progressively, what was history. I think that this provocation of the French parliament will not help the consciousness in Turkey," he said.