Almost 50 people are dead and dozens more wounded after ISIS militants hit the Syrian city of Qamishli with a deadly truck explosion on Wednesday morning. 

The death toll is expected to rise because of the number of people seriously wounded, according to the British-based Syrian Observatory for Human Rights. It is the deadliest attack on the city, which lies in north-east Syria near the Turkish border. 

At least 48 people are dead, although state media puts the figure at 44. The explosion was near a base for Kurdish security forces, who have been fighting the militant group.

Kurdish forces control much of Hasaka province, after capturing vast areas from the jihadist group last year. The Kurdish YPG militia, which has proved the most effective partner for a US-led coalition battling Islamic State, is also involved in fighting the extremists farther west, in Aleppo province.

Islamic State claimed responsibility for what it said was a suicide truck bomb attack, and added that it targeted Kurdish security forces. The group has carried out a number of bombings in Qamishli, which is in Hasaka province, and in the provincial capital, Hasaka city.

State TV rolled footage purportedly from the scene of one blast, showing large-scale damage to buildings, vast amounts of rubble strewn across the road and plumes of smoke rising.

The explosion was so powerful it shattered the windows of shops in the Turkish town of Nusaybin, directly across the border. Two people were slightly hurt in Nusaybin, said one witness.

In April a suicide blast killed six members of the Kurdish internal security force, known as the Asayish. And in July an Islamic State suicide bomb killed at least 16 people in Hasaka.

The YPG is now involved in a US-backed offensive that has advanced against the jihadists further west near the Turkish border.

The assault against Islamic State in the city of Manbij has put it under pressure, cutting off all routes out of the city. Fighters from the US-backed alliance have in recent weeks made incremental advances as they try to flush out the remaining IS fighters in Manbij.

Territory that Islamic State controls in that area was a major supply route to the outside world via the Turkish-Syrian border, through which it moved weapons and fighters.

Additional reporting from Reuters.