A truck bomb has exploded in the city of Al-Qamishli, Syria, killing nearly 50 people.

ISIS claimed responsibility for the attack and said that the bombing was in response to air strikes launched by US-led coalition forces in Manbij area.

The bomb allegedly targeted the area of the defence committee that is part of the self-managed democracy, according to the Syrian Observatory for Human Rights.

The number of dead is likely to increase as many were seriously injured in the blast that took place on Wednesday, the UK-based organisation said.

The militant group previously conducted bombings in Qamishli and Hasaka city, media sources reported.

"The number of dead is likely to increase as many were seriously injured in the blast that took place on Wednesday."

The explosion was initially believed to have been caused by two bombs. However, it now appears that the first blast was the gas tank exploding, according to AFP.

Meanwhile, the Syrian army has announced that pro-government forces are interrupting supply into ISIS-controlled Aleppo by tightening their grip on the province.

The largest Syrian city has now been seized by army personnel, who are calling on the militants in the region to surrender their weapons, SANA news agency reported.

The observatory announced that at least five civilians in the Mashhad district of Aleppo were killed on Tuesday after Syrian helicopters dropped barrel bombs in the region.

Image: ISIS has claimed responsibility for the truck bomb explosion in Al-Qamishli. Photo: courtesy of Syrian Observatory for Human Rights.