Hostilities had intensified on Friday night when attempts to repair a water pump supplying rebel districts were halted by a fierce bombardment.

In retaliation, the Suleiman al-Halabi pumping station serving the rest of the city was switched off yesterday.

Kieran Dwyer, spokesman for the UN children’s agency Unicef, said water was now being used as a weapon of war by both sides and warned the results could be ‘catastrophic’.

Mr Dwyer said the Bab al-Nairab pumping station supplying rebel-held parts of Aleppo was damaged on Thursday and subsequent strikes had made repairs impossible.