"There was a large explosion at dawn today in Hasakeh city caused by an Islamic State car bomb attack on a base belonging to the Kurdish internal security forces," the Syrian Observatory for Human Rights said.

The Britain-based group said IS militants opened fire on Kurdish forces after the blast, prompting fierce clashes.

All the attackers were killed, the Observatory said, without specifying the number of IS fighters involved in the assault in the provincial capital, where Kurdish and regime forces share control.

IS holds large areas of the countryside around the city and has attacked it on previous occasions.

Syrian state media reported a "terrorist car bomb" in Hasakeh city had left several dead and wounded, without giving a toll, and said the jihadists had also bombarded the city.

"IS terrorists targeted neighbourhoods (of Hasakeh city) with rockets and mortars," killing three people and wounding four more, the official news agency SANA said.

The Observatory said at least two people had been killed in the bombardment.