The Organization for the Prohibition of Chemical Weapons is investigating reports of a suspected chemical weapons attack on the Syrian rebel-held town of Douma, its head said Monday as the United States and European countries blamed the regime of Bashar Assad. The organization "made a preliminary analysis of the reports of the alleged use of chemical weapons immediately after they were issued," said director general Ahmet Uzumcu. More information was being gathered "to establish whether chemical weapons were used," he added. The suspected chemical attacks over the weekend killed at least 60 people and wounded more than 1,000, a Syria medical relief group said on Monday. The death toll is likely to rise, according to the Union of Medical Care Organizations, a coalition of international aid agencies that funds hospitals in Syria and which is partly based in Paris. "The numbers keep rising as relief workers struggle to gain access to the subterranean areas where gas has entered and hundreds of families had sought refuge," the group said in a statement. US President Donald Trump on Sunday blamed Syrian regime forces for what he called a "mindless CHEMICAL attack." He said there would be a "big price to pay". But Russian Foreign Minister Sergei Lavrov snapped back at Trump, saying allegations that the Syrian regime carried out the attack are a provocation. Russian specialists found no trace of chemical attack in Douma, Lavrov said. The Russian army had earlier accused Israel of carrying out deadly missile strikes on the central Syrian airbase of Tayfur from Lebanon before dawn on Monday.  Lavrov described the strike as a “very dangerous development.” French President Emmanuel Macron and Trump agreed in a phone call that chemical weapons had been used in Douma, the French presidency said in a statement early on Monday. They "exchanged their information and analysis confirming the use of chemical weapons," it said. "All responsibilities in this area must be clearly established," added the statement. Prime Minister Theresa Mays spokesman also said Britain is working with its allies to agree a joint response to the attack. In a separate statement, Britains Foreign Office said a full range of options should be on the table in response to the attack. As for Germany, it said the circumstances pointed to the Syrian regime. "The government condemns this new use of poison gas in the strongest terms," German government spokesman Steffen Seibert told a news conference. "The regimes actions are abhorrent." "Those responsible for the use of poison gas ... must be held to account," he added. "With this use of poison gas, the circumstances point to Assad regimes responsibility." The European Union also squarely blamed the regime. EU spokeswoman Maja Kocijancic said that over the weekend and early Monday as the reports came in of another atrocity in Syria, the EU "learned from several sources" to shape its conviction "that it is the Syrian regime which is responsible" when it comes to the suspected chemical attack.