Russia warns will retaliate if US strikes in Syria over 'false flag chemical attack'

Moscow will retaliate against any attack by the United States in Syria that threatens the lives of Russian servicemen, Russia's head of general staff has warned.

Valery Gerasimov told state-run Sputnik News on Tuesday that the US plans to strike government-held parts of Damascus in response to a "false flag chemical attack".

"After the false flag attack, the US plans to accuse the Syrian government troops of using chemical weapons, and to provide the world community with the so-called 'evidence' of the alleged mass death of civilians," Gerasimov said.

The general said that the US "plans to launch a missile strike on the government-held districts of Damascus" in retaliation to a "staged strike" in the rebel-held enclave of Eastern Ghouta.

Moscow has been one of the key allies of Syrian President Bashar al-Assad since it launched a military operation in the country, helping him turn the tide of war in his favour.

The warning from Russia's top military official comes a day after US ambassador to the UN Nikki Haley warned that Washington was prepared to take military action again for chemical attacks that are killing and injuring Syrian civilians.

The latest fighting in Syria's seven-year-old civil war has seen an uptick in the alleged use of chlorine gas attacks by the regime, in particular in Eastern Ghouta.

Syria's government has vehemently denied ever deploying chemical weapons.

US President Donald Trump last April ordered a missile strike against a regime airbase at Shayrat, after Washington said it used the facility to launch a sarin nerve gas attack on the rebel-held town of Khan Sheikhun, killing scores of civilians.

The use of chlorine as a weapon is banned under international law and Russia was supposed to oversee the destruction of Syria's chemical weapons arsenal.

Eastern Ghouta is the last opposition-controlled pocket near Damascus. For nearly three weeks, regime forces have pounded it in an assault that has killed over 1,000 civilians.