Theresa May has joined Barack Obama, Angela Merkel and the leaders of France, Canada and Italy to jointly condemn Russia over its role in the humanitarian disaster “taking place before our very eyes” in Aleppo.

In the statement, the six leaders criticised the Syrian government “and its foreign backers, especially Russia”, for attacks on civilians and obstructing humanitarian aid.

The statement, also released in the name of François Hollande, Justin Trudeau and Matteo Renzi, noted that 200,000 civilians, among them many children, were now cut off in eastern part of the Syrian city, which is under military siege.

“Aleppo is being subjected to daily bombings and artillery attacks by the Syrian regime, supported by Russia and Iran,” it said. “Hospitals and schools have not been spared. Rather, they appear to be the targets of attack in an attempt to wear people down. The images of dying children are heart-breaking.”

Warning that there should be consequences for anyone found to be committing war crimes in the city, the leader said there was an “urgent need” for a ceasefire, so the UN could bring in aid to those trapped, and relief to people who have fled.

The opposition have agreed the UN’s four-point plan for Aleppo,” the statement said. “The regime needs to agree the plan too.”

All parties fighting in Syria must obey international law, including the Geneva conventions, the leaders’ statement said.

They added: “United Nations secretary general, Ban Ki-moon, has spoken about war crimes being committed in Syria. There must not be impunity for those responsible. We call on the UN to investigate respective reports and gather evidence to hold the perpetrators of war crimes to account.”

We are ready to consider additional restrictive measures against individuals and entities that act for or on behalf of the Syrian regime.

“At the same time, Russia is blocking the UN security council, which is therefore unable to do its work and put an end to the atrocities. The regime’s refusal to engage in a serious political process also highlights the unwillingness of both Russia and Iran to work for a political solution despite their assurances to the contrary.”

The statement reiterated support for the UN’s special envoy for Syria, Staffan de Mistura, to resume negotiations. It finished: “Only a political settlement can bring peace for people in Syria.”

However, the statement contained no commitments to new action. Speaking later, the US ambassador to the United Nations, Samantha Power, told AP that diplomatic efforts appeared to have failed.

“Diplomacy has not delivered for the people of Aleppo,” she said. “It is not us that walked away from diplomacy. It is Syria and the Russian Federation.”

It comes as one of the last NGOs on the ground in Aleppo warned that civilians in the east were in fear of their lives. “People worry that Grozny will happen again. They have lost trust in everyone - in world leaders, in the international organisations that are watching them being killed. They lost faith in the United Nations. And they just count the days to their death,” said Dr Mounir Hakimi, the chairman of Syria Relief.

“Our priority now is ceasefire, get the civilians out. There are 500 injured people who need to be evacuated and get immediate medical help,” he said. “Pressure has to come from the public and the press to the politicians to pick up the phone, get the Russians to the table stop the bombardment.”

Syrian forces loyal to the regime of Bashar al-Assad are engaged in a brutal, weeks-long campaign in Aleppo’s east, during which hundreds of civilians have died. They have now retaken the historic Old City of Aleppo, long a bastion of the opposition.

Assad’s forces are the closest they have ever been to seizing the entire city, where a quarter of a million people are living without functioning hospitals and with dwindling food stocks.

Rebel fighters withdrew overnight from the Old City, abandoning it over fears of being cut off by the soldiers and Iranian-backed militias spearheading the regime assault.

The rebels called for a five-day ceasefire deal that would allow the evacuation of wounded civilians and offer a path out of the city to residents who wish to leave, amid conflicting reports of divisions within opposition ranks on whether to withdraw from Aleppo or commit to a last stand.





