The Islamic State group ordered residents to evacuate the Syrian city of Raqqa on Sunday following reports that a dam contested by US-backed forces upstream on the Euphrates River could collapse, activists reported.
The militants said coalition airstrikes had weakened the Tabqa Dam, some 40 kilometers (25 miles) west of Raqqa, and that the water level behind the dam was rising. The extremists captured the city from Syrian rebels in 2014 and it now serves as the capital of the group’s self-styled Islamic caliphate.
The group also said in messages carried on its social media channels that the dam’s operations had been put out off service and that all flood gates were closed.
The dam is the largest in Syria.
Civilians began fleeing midday, according to the activist-run group, Raqqa is Being Slaughtered Silently.
The US-backed Syrian Democratic Forces has been battling to capture the dam from Islamic State since Friday.
A Britain-based war monitor, the Syrian Observatory for Human Rights, said it had also learned from its own sources that the dam had stopped functioning but that Islamic State remained in control of its main operational buildings and turbines.
The dam is about 4 km long and the SDF has advanced a small distance along the dam from the northern bank but its progress is slow because Islamic State has heavily mined the area, the Observatory said.
The US-led coalition battling IS could not immediately be reached for comment.
The reports from Raqqa came as a leading Syrian opposition group called on the US-led coalition to stop targeting residential areas in and around the city.
The Syrian National Coalition said in a statement that it was “increasingly concerned” about civilian casualties in the campaign against the extremist group. The exiled opposition coalition is taking part in U.N.-mediated talks in Geneva.
The SNC said it believed coalition forces were behind an airstrike that killed at least 30 civilians sheltering in a school in the countryside outside Raqqa on March 21. The coalition has said it is investigating.
The US has provided substantial air and ground support to the Kurdish-led Syrian Democratic Forces, who are closing in on Raqqa as well as the Tabqa Dam.
The Britain-based Syrian Observatory for Human Rights said coalition airstrikes have killed 89 civilians in the Raqqa province in the past week, including 35 in the Badya school, in the village of Mansoura.