The fight for the Syrian city of Aleppo "is beyond doubt one of the most devastating urban conflicts of modern times," the head of the International Committee of the Red Cross (ICRC) said on Monday.
"Besides the direct threat posed by the fighting, the lack of essential services such as water and electricity, poses an immediate and dramatic risk for up to two million people, who have great difficulty in accessing basic medical care," ICRC president Peter Maurer said.
The ICRC echoed calls by the UN for regular humanitarian pauses in fighting to allow humanitarian aid in and give enough time to carry out repairs to essential services.
It said all parties to the conflict must allow humanitarian agencies to reach civilians across the divided city, where rebels are battling forces loyal to Syrian President Bashar al-Assad.
"No one and nowhere is safe. Shell-fire is constant, with houses, schools and hospitals all in the line of fire. People live in a state of fear. Children have been traumatized. The scale of the suffering is immense. For 4 years, the people of Aleppo have been devastated by brutal war, and it is only getting worse for them," Maurer said.
Fighting in Aleppo has intensified since early last month, when government forces captured the last supply route to the rebel-held eastern sector of the city, raising fears that its estimated 250,000 to 300,000 remaining residents could suffer a lengthy siege.
On August 5, rebels broke through government lines to open a new route into the east, but with fierce fighting continuing in the area, it is not clear whether they will be able to bring adequate supplies in.
Their advance also threatened supply lines to government-held western Aleppo, with an estimated population of 1.2 million, while the intensified fighting has resulted in loss of electricity and drinking water supplies across the city.
The UN has called for weekly 48-hour humanitarian pauses in the fighting, and has dismissed a series of three-hour pauses announced by Syrian government ally Russia last week as inadequate.