Turkey threatened more sanctions for France if the Senate in Paris votes to make it a crime to deny the 20th-century killing of Armenians by Ottoman Turks constitutes a genocide.
France's lower house voted to make such denials a crime last month, prompting Turkey to suspended military, economic and political ties. If the bill passes the Senate, it will be on a fast track to becoming law. If it fails, the National Assembly, France's lower house, could take it up again, starting the process over.
As the debate before the vote got under way, rival demonstrations — one pro-Turkish and one pro-Armenian, kept apart by a large police presence — gathered outside the upper house of parliament, waving flags and blowing whistles.
On Saturday, thousands of Turks from across Europe marched through the French capital, accusing French President Nicolas Sarkozy of acting in the hope of securing French Armenians' votes in this year's presidential elections.
An estimated 500,000 Armenians live in France.
While most historians contend that the 1915 killings of 1.5 million Armenians as the Ottoman Empire broke up was the 20th century's first genocide, Turkey has vigorously denied that. It says that there was no systematic campaign to kill Armenians and that many Turks also died during the chaotic disintegration of the empire.
On Monday, Turkish Deputy Prime Minister Bulent Arinc, speaking during a visit to Strasbourg, France, said: "What would happen if a thousand, ten thousand or a hundred thousand gathered around Eiffel and said 'there is no genocide'? What would the French justice do? Would it be able to convict ten thousand or a hundred thousand people? I don't think so."
But the most significant protest came from Ankara, Turkey's capital, where the foreign minister warned that he was ready to take new measures against France if the bill passed.
"Turkey will continue to implement sanctions as long as this bill remains in motion," Turkish Foreign Minister Ahmet Davutoglu told reporters ahead of the debate. "We hope however, that this won't be necessary and that common sense will reign in the French Senate."
He did not spell out the measures Turkey would take.
The bill sets a punishment of up to one year in prison and a fine of €45,000 ($59,000) for those who deny or "outrageously minimize" the killings — putting such action on par with denial of the Holocaust.
France formally recognized the 1915 killings as genocide in 2001, but provided no penalty for anyone rejecting that.
The bill strikes at the heart of national honor in Turkey, which has argued that the bill would compromise freedom of expression in France.
"European values are under threat," Davutoglu said Monday. "If each parliament takes decisions containing its own views of history and implements them, a new era of Inquisition will be opened in Europe."
"Those who voice views that exclude this view of history will be jailed," he said. "It would unfortunately, be a great shame for France to revive this."