Syrian regime forces 'will attack' US-backed fighters in Raqqa

Syrian regime fighters will advance on the former Islamic State group stronghold of Raqqa an Iranian official has said, which is now held by the US-backed Syrian Democratic Forces.

Leading Iranian politician Ali Akbar Velayati said that Syrian regime forces will advance on Raqqa after capturing neighbouring Deir az-Zour province from IS.

"We will witness in the near future the advance of government and popular forces in Syria and east of the Euphrates, and the liberation of Raqqa city," he said, according to Reuters.

Raqqa was the de-facto capital of IS until US-backed Syrian Democratic Forces captured the Syrian city last month following a long and bloody campaign.

As the Kurdish and Arab SDF pushed southwards it has put them into conflict with the Syrian regime on the other side of the Euphrates River.

Iran has been a key backer of Bashar al-Assad throwing in thousands of militia fighters to bolster the regime's decimated forces.

Syrian regime ally Russia has tried to calm tensions with a ceasefire zone, but the two sides appear deadlocked.

Damascus has made it clear that it considers Raqqa part of its territory and want it reincorporated into its territory.

Kurdish fighters make up the bulk of the Syrian Democratic Forces, particularly those aligned to the People Protection Units (YPG).

Damascus fears the area under YPG control - known as Rojova - is being set up at a mini-state.