Fighters battle IS around key town

US-backed forces battled the Islamic State group around a key Syrian town yesterday, hours after the capture of an airbase brought them closer to besieging the jihadists in their stronghold Raqa.

Backed by air power from the US-led coalition that has been bombing IS since 2014, the Syrian Democratic Forces (SDF) are laying the groundwork for an assault on the heart of the jihadists' so-called "caliphate."

Operations are currently focused on the strategically important town of Tabqa on the Euphrates River, and the adjacent dam and military airport.

Late Sunday, Arab and Kurdish fighters from the SDF seized Tabqa airbase and pressed north towards the town itself.

The base is approximately 2.7 kilometres south of Tabqa.

Bolstered by air strikes and military advisers from the US-led coalition, SDF units are approaching Tabqa from the south via the airport and the north near the dam.

Abdel Rahman said the SDF was locked in fierce clashes on Monday near the northeastern entrance of the dam.

The SDF launched its offensive for Raqa city in November, seizing around two thirds of the surrounding province, according to the Britain-based Observatory.

At their closest point, they are just eight kilometres (five miles) from the city, to the northeast.

But they are mostly further away, between 18 and 29 kilometres from Raqa.