Intense airstrikes overnight drove Syrian rebels back from the edge of Hama, a major city whose fall would pile pressure on President Bashar al-Assad, both sides said on Wednesday.

Syrian rebel forces arrived at the gates of the key city of Hama on Tuesday, as their fighting with the military sparked "a large wave of displacement", a war monitor said.

Syrian rebel troops threatening to topple President Bashar Al Assad reached Hama after making key territorial gains in Aleppo, even as the US and Russia, on opposite sides in the renewed civil war, accused each other of supporting terrorism.