DAMASCUS, Syria — A team of inspectors from the international chemical weapons watchdog was on its way to Syria on Thursday to begin an investigation into a suspected chemical weapons attack near the capital that has brought the war-torn country to the brink of a wider conflict, amid Western threats of retaliation and Russian warnings of the potential for “a dangerous escalation.”

The fact-finding mission from the Organization for the Prohibition of Chemical Weapons was expected to head to Douma, where the suspected attack took place and where Russia said rebels had now capitulated to government control.

The Syrian government said it would facilitate the mission’s investigation, which was to begin Saturday.

Syria and its ally, Russia, deny any such attack, which activists say killed more than 43 people last weekend.

Speaking at the United Nations on Thursday, Russia’s U.N. ambassador, Vassily Nebenzia, said the top priority had to be to avert a wider war, and he didn’t rule out the possibility of a U.S.-Russia conflict.

Speaking to reporters after a closed emergency meeting of the U.N. Security Council, Nebenzia said Russia was very concerned with “the dangerous escalation” of the situation and “aggressive policies” and preparations that some governments were making – a clear reference to the Trump administration and its allies.

“We hope that there will be no point of no return – that the U.S. and their allies will refrain from military action against a sovereign state,” Nebenzia said, adding that “the danger of escalation is higher than simply Syria.”

The imminent arrival of the chemical weapons inspectors came as rebels in Douma surrendered their weapons and left the town for opposition-held areas in the north. Russia’s military said Thursday that Douma was now under full control of the Syrian government after a Russian-mediated deal secured the evacuation of the rebels and thousands of civilians after it was recaptured by Syrian forces.

Douma and the sprawling eastern Ghouta region near the capital, Damascus, had been under rebel control since 2012 and was a thorn in the side of President Bashar Assad’s government, threatening his seat of power with missiles and potential advances for years.