The Syrian Democratic Forces, backed by the US, have declared a new offensive to capture Raqqa from Isis, according to Reuters.

The city has become the de-facto capital of the extremist group.

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 are attempting to encircle the city and cut off supply lines to Isis.

US President Donald Trump reportedly scrapped existing plans for recapturing Raqqa, drawn up by the Obama administration, earlier this week.

It is unknown if the offensive has been influenced by the change in White House policy.

The city was captured by Isis in 2014 and is their last major urban stronghold in Syria.

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A confrontation has been drawing closer in recent weeks, with nearby fighting becoming more frequent as the SDF have been closing in.

In addition, US-led coalition aircraft destroyed the main water pipeline supplying the city, as well as two bridges, though the water supply was later repaired by Isis.