Beirut: A large truck bomb blast claimed by IS killed nearly 50 people and wounded scores more in the northeastern Syrian city of Qamishli near the Turkish border on Wednesday, a monitoring group and state television reported.
The attack, which hit near a Kurdish security forces headquarters, was the deadliest of its kind in the city for years, the British-based Syrian Observatory for Human Rights said.
The blast, which took place early on Wednesday, killed at least 48 people. The death toll expected to rise because of the number of people seriously injured, the Observatory said. State media put the death toll at 44.
Kurdish forces control much of Hasaka province, after capturing vast areas from the militant group last year. The Kurdish YPG militia, which has proved the most effective partner for a US-led coalition battling IS, is also involved in fighting the extremists farther west, in Aleppo province.
IS claimed responsibility for what it said was a suicide truck bomb attack, and added that it targeted Kurdish security forces. The group State 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, a witness said.
IS has targeted Qamishli and the provincial capital, Hasaka city, in the past with bombing attacks. A suicide blast killed six members of the Kurdish internal security force, known as the Asayish, in April. In July, an IS suicide bomb killed at least 16 people in Hasaka.
The YPG is now involved in a US-backed offensive that has advanced against the militants further west near the Turkish border.
The assault against IS 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 IS 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.
Meanwhile, The Syrian army said on Wednesday it had cut off all supply routes into eastern Aleppo, and the government air-dropped thousands of leaflets there, asking residents to cooperate with the army and calling on fighters to surrender.
President Bashar Al Assad's initiative comes a day after the United Nations said it hopes to restart peace talks in August.
Previous attempts at a diplomatic solution to end Syria's five-year-old civil war collapsed in April, partly due to an uptick in violence in Aleppo.
On Tuesday, the army texted residents to ask them to leave the city and to give up their weapons.
An advance by pro-government forces around the only remaining supply route into the eastern sector this month enabled them to fire on it at close range, making the battlefront Castello road too deadly to use and putting at least 250,000 people in rebel-held districts under siege.
"(Armed forces) have cut all supply routes and crossings which terrorists used to bring mercenaries, weapons and ammunition into the eastern neighbourhoods of Aleppo," a statement from the Syrian military general command said.
The government refers to all rebels as terrorists.
The Britain-based Syrian Observatory for Human Rights said eastern Aleppo had been under effective siege since July 11, and advances in recent days by pro-government forces had strengthened their control of the only route in.
"Today there is no way at all to bring anything into Aleppo," Observatory Director Rami Abdulrahman said.
Syrian government forces and their allies also seized territory from rebels outside Damascus, encroaching on a pocket of insurgent-held land east of the capital, the Syrian Observatory for Human Rights and state media reported.
The advance took place overnight near the town of Hosh Al Fara area in the Eastern Ghouta suburb, the British-based monitoring group said.
Quoting a military source, Syrian state news agency SANA said government and allied forces took control of a farming area south-east of Hosh Al Fara during the day on Wednesday.
Fighting around the capital has intensified according to the Observatory, and government forces have stepped up their bombardment of rebel-held areas. A rare bout of rebel mortar fire on government-controlled central Damascus on Sunday killed several people.
The Observatory said government helicopters had dropped dozens of barrel bombs on Douma on Monday, and jets had carried out air strikes on Daraya, another besieged area in Damascus's southwestern suburbs.