Kremlin ambassador to Lebanon said any U.S. missiles fired at Syria would be shot down and the launch sites targeted, a step that could lead to a major escalation in the Syrian war.

Russian Ambassador Alexander Zasypkin said in Arabic to a TV channel, that he was referring to a statement by Russian President Vladimir Putin and the Russian armed forces chief of staff.

The United States and its allies are considering whether to hit Syria over a alleged poison gas attack that medical relief organisations say killed dozens of people in the rebel-held town of Douma near Damascus during weekend.