Fierce fighting between so-called "Islamic State" (IS) jihadists and the Kurdish Syrian Democratic Forces (SDF) at the Tabqa Dam has put it out of service. A technical source from Syria told the AFP news agency that water levels in the reservoir were rising, which could inundate the surrounding area.

The dam is located some 40 kilometers (25 miles) west of Raqqa. Three years ago, IS militants captured the city, which now serves as the Islamist group's "caliphate."

"Shelling on the area… that supplies that damn with electricity has put it out of service," a source at the dam told AFP. "The work needed to fix the problem is not possible because there is not sufficient staff available as a result of the intensive shelling in the area of the dam."

But the UK-based Syrian Observatory for Human Rights reported that the IS-held dam was out of order for unknown reasons.

'Catastrophic' implications

On Sunday, IS fighters ordered Raqqa residents to evacuate the city. The militants claim that the US-led coalition's airstrikes had weakened the dam.

Through its propaganda agency, IS issued warnings that the dam "is threatened with collapse at any moment because of American airstrikes and a large rise in water levels."

The US-backed Kurdish-Arab alliance, SDF, denied damaging the dam during last week's assault. "We carried out this operation to land there to avoid shelling or damage to the dam," Talal Sello, an SDF spokesman, told media.

Earlier this month, the United Nation's humanitarian coordination agency OCHA confirmed that water levels in the Euphrates River had risen 10 meters (33 feet) since late January, partly because of heavy rain and snow. But the organization warned that damage to the Tabqa Dam "could lead to massive scale flooding across Raqqa and as far away as Deir Ezzor" province to the southeast.

Any further increase in the dam's water levels or damage "would have catastrophic humanitarian implications in all areas downstream," the UN warned.

shs/jm (AFP, AP)