Turkey and France on Tuesday issued warnings against the perpetrators of the chemical attack in Syria’s Douma town in Eastern Ghouta over the weekend. Turkish President Recep Tayyip Erdogan vowed that those behind the killings of civilians in the rebel enclave would pay a "heavy price". "I curse those who carried out this massacre. Whoever has done this, the perpetrators will be brought to account and certainly pay a heavy price," Erdogan told a meeting of his party in parliament. The Turkish foreign ministry at the weekend said there was a "strong suspicion" that the regime of Bashar Assad was responsible for the attack that left dozens dead. The Turkish leader on Monday expressed "concern" to Russian President Vladimir Putin over the attacks in Eastern Ghouta, the Turkish presidency said. Rescue workers said dozens of civilians had been killed in a chlorine gas attack on Douma -- claims denied by Assads regime and its ally Russia. In France, government spokesman Benjamin Griveaux said Tuesday Paris will retaliate against the regime if evidence emerges that it was behind the attack. "If the red line has been crossed, there will be a response," he told Europe 1 radio, adding that intelligence shared by President Emmanuel Macron and US President Donald Trump "in theory confirms the use of chemical weapons." In a phone call Monday night, the two leaders again discussed the latest chemical attack in Syria. Rescuers and medics in Douma say more than 40 people died after the poison gas attack. France has repeatedly warned that evidence of the use of chemical weapons in Syria is a "red line" that would prompt French strikes on Syrian regime forces. Trump for his part said Monday that "we have a lot of options militarily and well be letting you know pretty soon... probably after the fact." He added that the chemical weapons attack would be "met forcefully" and indicated a decision on military action was hours away. Russias UN ambassador on Monday warned that the use of military force against Syria could have "grave repercussions." In April last year, Trump launched a cruise missile strike against a Syrian air base after a previous chemical weapons attack UN monitors later pinned on Assads regime. The UN Security Council, gathered in New York, is expected to vote as Tuesday on rival US and Russian proposals to probe chemical attacks in Syria. Moscow has denounced the claims as "fabrications", with its UN envoy warning Monday that the possibility of military action was "very, very dangerous". Russian Foreign Minister Sergei Lavrov on Tuesday said Moscow will propose a UN resolution to investigate chemical weapons attacks in Syria, after Russia rejected a similar move from the US. Lavrov said Russia would propose a "transparent and honest" investigation with the involvement of the Organization for the Prohibition of Chemical Weapons at the Security Council. The Russian military said on Monday it had found no traces of a chemical attack in Douma, Interfax news agency reported. The defense ministry said Russian military medics had examined patients in a hospital in Douma and found no symptoms of chemical poisoning, according to the agency. It revealed that its specialists visited hospitals in Douma, the largest town in the Eastern Ghouta region outside Damascus, but found no evidence of a chemical attack. Meanwhile, evacuations continued in Douma as opposition factions agreed to surrender after it was hit by the chemical attack. Sixty-seven buses carrying hundreds of opposition faction members, along with family members and other civilians who did not wish to come back under Assad’s rule, reached opposition areas near Aleppo on Tuesday, the Syrian Observatory for Human Rights said.