A U.N. official says nearly 2 million people in the northern Syrian city of Aleppo are without running water as security conditions deteriorate.

Hanaa Singer, UNICEF representative in Syria, says intense attacks after midnight Thursday have damaged the Bab al-Nairab station that supplies some 250,000 people in rebel-held eastern parts of the contested city with water.

Singer said that in retaliation, the Suleiman al-Halabi pumping station, also located in the rebel-held east, was switched off — cutting water to 1.5 million people in government-held western parts of the city.

"Depriving children of water puts them at risk of catastrophic outbreaks of water-borne diseases," Singer warned in her statement released late Friday.

Fighting in Aleppo intensified recently after a one-week U.S.-Russia-brokered cease-fire collapsed.