Syrian Kurdish activists and the Kurdish People's Protection Units (YPG) have denied claims that the Islamic State of Iraq and the Levant (ISIL) has recaptured a Syrian town from Kurdish-led forces near Raqqa city.
The UK-based Syrian Observatory for Human Rights said on Monday that ISIL forces had taken Ayn Issa and surrounding areas from the YPG, which only seized the town from the armed group's control two weeks ago.
However, Kurds said that fighting was still going on at the perimeter of the town and some points inside it, just two days after it was pummelled in heavy US-led air strikes.
Elsewhere in Syria, deadly clashes took place on Monday between YPG forces and ISIL fighters for control of Syria's northeastern Hasakah province, the observatory reported.
ISIL claimed it killed at least 50 Kurdish fighters during the clashes on Monday, after they reportedly captured several checkpoints in Hasakah city's suburbs, sources told Al Jazeera.
Two car bombs exploded near government checkpoints in southern Hasakah, killing at least 11 government forces.
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Syrian government warplanes have bombed southern Hasakah repeatedly over the past few days, targeting ISIL strongholds near al-Ahdath prison and an electricity tower.
ISIL launched its offensive on the northeastern province, which borders Turkey, on June 25.
ISIL moved closer to Hasakah city last month, but the city remains under opposition and YPG control.
The UN said at least 120,000 have been displaced due to the fighting within Hasakah city and its surrounding villages.
Execution in Raqqa
Earlier on Monday, ISIL released a new video purporting to show the killing of two Syrian men in the armed group's stronghold of Raqqa, allegedly for spying on the group.
The video, which was posted on an ISIL-linked Facebook page, showed two young men in orange jumpsuits, saying they filmed and photographed ISIL-held areas in Syria and sent footage to a person abroad.
They identified themselves as 21-year-old Faysal Hussein Habibi and 20-year-old Bishr Abdul-Azim and say they received $400 a month for the filming. The two are then tied to a tree, after which masked gunmen shoot them in the head at close range.
The video could not be independently verified but it was posted on a page known to be linked to the militant group.
Source: Al Jazeera and agencies