Fighters from the Syrian Democratic Forces gather near a village north-east of Raqa on February 3, 2017, during their advance on the militant’ de facto capital in Syria.

An alliance of US-backed militias said it had started a new phase of its campaign against the ISIS-held city of Raqqa on Saturday, aiming to complete its encirclement and sever the road to militant strongholds in Deir al-Zor province.

The Syrian Democratic Forces (SDF) said in a statement the action was being undertaken with “increasing support from the (US-led) international coalition forces through guaranteeing air cover for our forces’ advances, or via the help provided by their special teams to our forces on the battle ground”.

The SDF, which includes the powerful Kurdish YPG militia, launched its multi-phased campaign aimed at encircling and ultimately capturing Raqqa in November.

A SDF commander told Reuters the forces had so far advanced a few kilometres (miles) in the latest phase, which aims to capture areas to the east of the city, including the highway linking it to Deir al-Zor province.

Deir al-Zor, which is almost entirely in ISIS hands, stretches all the way to the Iraqi border. A Kurdish military source told Reuters on Tuesday that the goals of this phase included capturing the main highway.

Several hundred US special forces soldiers have been supporting SDF operations against ISIS in northern Syria. France said in June that its special forces were advising rebels in the same area.

[vuukle]