A deal hammered out by Russia, Turkey and Iran to set up "de-escalation zones" in mostly opposition-held parts of Syria has gone into effect.

America has dismissed an eight-hour pause in attacks by Russian and Syrian forces on rebel-held eastern districts of Aleppo as "too little, too late".

Russian and Syrian forces are preparing a "humanitarian pause" for the besieged city of Aleppo on Thursday, the head of Russia's military general staff said.

A Syrian government airstrike on an opposition-held district in Aleppo has killed at least two people.

Russia's deputy defence minister has accused Turkish president Recep Tayyip Erdogan and his family of personally profiting from oil trade with militants from the so-called 'Islamic State' group.