US coalition strike on pro-Assad forces an 'act of aggression': Lavrov

Moscow on Wednesday condemned a US-led coalition strike on pro-regime fighters in Syria as an "act of aggression" that targeted the most effective forces battling "terrorists" in the war-torn country.

"It was an act of aggression which breaches the territorial sovereignty of Syria and intentionally or not targeted those forces that are the most effective in fighting the terrorists on the ground," Foreign Minister Sergei Lavrov said.

The US-led coalition on Tuesday said it had destroyed a unit of pro-regime forces in Syria as they advanced near an area where coalition commandos have been training and advising rebels.

A group of about 60 pro-regime soldiers moved into the area with a tank, artillery, anti-aircraft weapons and armed technical vehicles, the coalition said in a statement. They posed a threat to the coalition forces at At-Tanf Garrison near the border with Jordan and Iraq, it added.

The assault marks the second time in less than a month that coalition forces have attacked pro-regime fighters as they headed toward the garrison inside a supposed "deconfliction zone" claimed by the US.

Russian deputy foreign minister Sergei Ryabkov told news agencies that "as far as we understand" the pro-regime forces hit on Wednesday "posed no military threat" to coalition troops.

Ryabkov accused the US of trying to impose its plan for Syria by force as Russia, Iran and Turkey are pushing a separate attempt to shore up their own "de-escalation zones" around the country.

Russia is flying a bombing campaign in Syria in support of leader Bashar al-Assad, while the US is heading a coalition mainly targeting IS.