Aleppo

The Russian Defense Ministry had called for the ceasefire -- termed a "humanitarian pause" -- so rebels, civilians and medical cases could evacuate Aleppo during daylight hours without fear of being struck by bombs.

But it appears few, if any, actually left the besieged city.

The UK-based Syrian Observatory for Human Rights said Saturday it didn't know of anybody who evacuated using any of the eight corridors announced by the Syrian regime and Russia.

US Secretary of State John Kerry described the situation as "the largest of humanitarian disasters".

He said that Russia needed to understand that "this war cannot end without a political solution".

Mr Kerry is in London taking part in talks aimed at finding a peaceful solution to the Syria conflict.

Speaking alongside the UK's Foreign Secretary Boris Johnson, he said that "crimes against humanity" were taking place daily in Aleppo.

Mr Johnson also urged Russia to "do the right thing by humanity and the people of Syria" by committing to a ceasefire.

Aleppo, Syria's second city, has been split in two during the country's long conflict. Daily life has become a struggle for those still living there, caught in the fight between rebel and government forces.

Bana's tweets in English - helped by her mother, a teacher - are bringing fresh attention to the struggles they face in rebel-held eastern Aleppo.

In one, Bana appears with her brothers - five-year-old Mohamed, and Noor, three - with the message "drawing with the brothers before the planes come. We need peace to draw."

The Syrian American Medical Society, which supports the hospital, said it had been struck by barrel bombs.

The same facility was hit in a similar attack on Wednesday.

There are also reports of Russian-backed Syrian government forces hitting Aleppo's historic Old City.

And clashes between government troops and rebels on the ground are said to be occurring in several Aleppo neighbourhoods.

Russian and Syrian air forces resumed attacks on the rebel-held east of the city after a partial truce lapsed on 19 September.

In a phone call with Sergei Lavrov, Mr Kerry said the US held Russia responsible for the use of incendiary and bunker bombs against the city.

The US state department said it was making preparations to suspend talks.

Aleppo has come under heavy aerial bombardment since the end of a ceasefire a week ago.

In response to Mr Kerry's phone call, the Russian Deputy Ambassador to the UN, Evgeny Zagaynov, said the "trend" of Russia being blamed for the attacks in Syria must stop.

The UN children's agency says fierce strikes on Friday prevented repairs to a damaged pumping station supplying rebel-held districts of the city.

In retaliation, Unicef says, a nearby station pumping water to the rest of Aleppo has been switched off.

Fresh strikes were reported in the city on Saturday, as the Syrian army presses on with its push to retake rebel areas.

The latest offensive was launched after a ceasefire collapsed on Monday.

Jets pounded rebel positions in the city on Wednesday night as a week-old truce collapsed, reportedly killing at least 13 people.

It is unclear whether the new offensive will involve ground troops.

Talks between the US and Russia on reviving the collapsed ceasefire have broken up without progress in New York.

Russia and the US support Syria's government and opposition respectively.

Several people were injured, the UK-based Syrian Observatory for Human Rights said, but it did not say who carried out the strikes.

Russia has said the future of the truce is in doubt after the US-led coalition struck the Syrian army in Deir al-Zour.

A Syrian political adviser told the BBC the US strike could not be a mistake.

The cessation of hostilities brokered jointly by the US and Russia does not exclude attacks on IS or other jihadist groups.

It is hoped that emergency aid deliveries will start on Wednesday.

Russian forces are monitoring the ceasefire along a key access road in northern Syria that leads to rebel-held eastern Aleppo, reports say.

Some 250,000 civilians are trapped there.

UN Special Envoy for Syria Staffan de Mistura said if the truce held, aid deliveries "should be taking place very, very soon".

He said the UN was waiting for the Syrian government to authorise deliveries and he hoped the people of Syria could look forward to "no bombs and more trucks".

Volunteer emergency workers say people suffered breathing difficulties after an attack on the Sukari area.

The reports could not be independently verified. AUN-led investigation in August found the government had used chlorine on at least two occasions.

The Syrian government has always denied using chemical weapons.