Reuters - Russia has warned that any U.S. missiles fired at Syria over a suspected chemical weapons attack on a rebel enclave would be shot down and the launch sites targeted, raising the possibility of a U.S.-Russian confrontation.

Issuing the warning on Tuesday evening, the Russian ambassador to Lebanon also said such a clash should be avoided and Moscow was ready for negotiations. But his remarks could raise fears of direct conflict for the first time between major powers backing opposing sides in Syria�s protracted civil war.

Moscow and Washington sparred at the United Nations on Tuesday over the use of chemical weapons in Syria as Washington and its allies considered whether to strike at Syrian government forces over the alleged poison gas assault.

At least 60 people were killed in Saturday�s suspected chemical weapons attack on the town of Douma, Syrian relief workers said. An estimated 500 people were being treated for �symptoms consistent with exposure to toxic chemicals�, the World Health Organization said on Wednesday.

The Syrian government and Russia say the reports are bogus. The Kremlin said on Wednesday it hoped all sides involved in Syria would avoid doing anything that could destabilize an already fragile situation in the Middle East, and made clear it strongly opposed any U.S. strike on its ally.

After the attack, the rebel group holed up in Douma - Jaish al-Islam - finally agreed to withdraw from the town. That sealed a big victory for President Bashar al-Assad, who has now crushed the rebellion in the eastern Ghouta region near Damascus.

On the diplomatic front, Moscow and Washington stymied attempts by each other in the U.N. Security�Council on Tuesday to set up international investigations into chemical weapons attacks in Syria. [

U.S. President Donald Trump on Tuesday canceled a planned trip to Latin America later this week to focus instead on talks with Western allies about possible military action to punish Assad for the suspected gas attack on a rebel-held town that had long withstood a devastating Syrian government siege.

Trump had on Monday warned of a quick, forceful response once responsibility for the attack was established.

�If there is a strike by the Americans, then ... the missiles will be downed and even the sources from which the missiles were fired,� Alexander Zasypkin, the Russian ambassador in Beirut, told Hezbollah�s al-Manar TV, speaking in Arabic.

He said he was referring to a statement by Russian President Vladimir Putin and the Russian armed forces chief of staff.

The Russian military said on March 13 that it would respond to any U.S. strike on Syria by targeting any missiles and launchers involved. Russia is Assad�s most powerful ally and its devastating air power has helped him wrest back large swathes of territory from rebels since 2015.