A US-backed Syrian force has captured a neighbourhood of the Islamic State group’s de-facto capital of Raqqa after two days of fierce fighting.

The Kurdish-led Syrian Democratic Forces said its fighters took Romaniah, north west Raqqa, on Sunday.

Syrian forces patrolling on the outskirts of the Syrian town of Manbij, in Aleppo province
The Syrian force is backed by the US (Arab 24 network, via AP, File)

The fighting left 12 IS gunmen dead, including a commander known as Abu Khattab al-Tunsi.

The Britain-based Syrian Observatory for Human Rights said SDF fighters now control Romaniah and the eastern neighbourhood of Mashlab. The fighters have also entered Raqqa’s western neighbourhood of Sabahiya.

Members of the Syrian Democratic Forces gather after a training session at a firing range in northern Syria
(AP Photo/Robert Burns)

SDF fighters began their offensive on Raqqa city on June 6 under the cover of airstrikes by the US-led coalition.

The battle is likely to be long and difficult as the extremist group is expected to fiercely defend its self-declared capital.