US Secretary of State John Kerry says America will cut off contact with Moscow over Syria unless attacks on Aleppo are stopped.

The State Department says Mr Kerry issued the ultimatum in a telephone call to Russian Foreign Minister Sergey Lavrov.

It comes as two hospitals were badly damaged and eight people killed as government forces intensified attacks on rebel-held parts of Aleppo.

Drone footage shows Aleppo destruction

Medical officials said an airstrike had knocked out generators and cut off the water supply at the M10 hospital - killing two seriously ill patients.

Another medical centre was struck by artillery fire, killing six people queuing for bread at a nearby bakery.


Adham Sahloul, of the Syrian American Medical Society, described the attacks as deliberate.

He said: "With these two hospitals gone, if today there is another offensive like Saturday or Sunday, this is signing the death warrant for hundreds of people."

It was unclear if the strikes were executed by Syrian or Russian forces, both of which are carrying out raids in Aleppo.

Mr Kerry's spokesman, John Kirby, says the politician expressed grave concern over the situation in Syria's second city.

He told Mr Lavrov the US holds Russia responsible for the use of incendiary and bunker-buster bombs in an urban area, Mr Kirby said.

During the call, he said the US was preparing to "suspend US-Russia bilateral engagement on Syria".

This includes a proposed counter-terrorism partnership, "unless Russia takes immediate steps to end the assault on Aleppo" and restore a ceasefire.

Mr Kerry and Mr Lavrov have been leading international efforts to bring the five-year-old civil war to an end, and on September 9 agreed to demand a ceasefire.

However, fighting continued and the truce collapsed after just a week.

:: Why the latest Syrian ceasefire was doomed from the start

Image: A wounded woman is taken to hospital in Aleppo

Reports from Russia say that during the call, Mr Lavrov urged Mr Kerry to make good on American pledges to separate Washington-oriented units of Syrian opposition from "terrorist groups".

He said warlords from militants formerly known as the Nusra Front had openly spoken about foreign support, including supplies of US weapons, the Russian Foreign Ministry said.

Meanwhile, UN chief Ban Ki-moon has described the situation as worse than a "slaughterhouse" during a speech at a UN Security Council meeting on healthcare in armed conflict.

"Those using ever more destructive weapons know exactly what they are doing - they know they are committing war crimes," he said, in an indirect attack on Syria and Russia.

Mr Ban said hospitals, clinics, ambulances and medical staff were "under attack around the clock," and called for "action" and "accountability".

Image: UN Secretary General Ban Ki-moon says the situation in Aleppo is worse than a 'slaughterhouse'

Pope Francis has warned those behind the bombing of the city will have to "answer before God".

During a weekly address at the Vatican, he referred to Aleppo as a "battered city where children, the elderly, the sick, the young, the old are dying".

He said: "I appeal to the conscience of those responsible for the bombardment, who will have to answer before God."

Image: Medics inspect the damage outside a field hospital after an airstrike

More than 250,000 people are thought to be besieged in the rebel-held part of Aleppo, where intensive bombing has killed hundreds of people since the collapse of a week-long ceasefire.

The Syrian army took control of rebel-held district Farafra on Tuesday, its first advance since Damascus announced it would retake the whole of the divided city.

Image: Drone footage shoes damaged buildings in one of the hardest-hit areas in Aleppo

The push by troops came after the UN's top envoy to Syria accused the government of "unprecedented military violence" against civilians.

Meanwhile, the World Health Organization has called for dozens of sick and wounded people in eastern Aleppo to be given safe passage so they can be treated.