United Nations Secretary-General Ban Ki-moon Friday warned of water shortages to at least 2.5 million people in the besieged northern Syrian city of Aleppo, blaming rebels for the disruption of the service, Al Arabiya reported.
Ban's office said the water supplies had been cut for eight days and called for the services to be restored immediately.
Al-Nusra Front, Al-Qaeda's Syrian branch, was among the rebel groups that cut the water supplies, though the Red Crescent said that some services had been restored.
According to the U.N. chief's office, Ban said "that preventing people's access to safe water is a denial of a fundamental human right."
"Deliberate targeting of civilians and depriving them of essential supplies is a clear breach of international humanitarian and human rights law," he said.
The U.N. chief called on all parties to "ensure that the water supply in Aleppo -- and everywhere in Syria - is permanently restored and to refrain from targeting civilian facilities and infrastructure."
Rebel rocket fire killed 13 people in Aleppo earlier, while troops launched an offensive on rebels in Daraa province of southern Syria, state media said.
The Syrian Observatory for Human Rights also reported the bloodshed in Aleppo and said a large-scale army operation was under way in Daraa for control of hills held by rebels.