US warns it could end cooperation with Russia over Syria airstrikes

 The US accuses Russia of driving moderate rebels into the arms of jihadists

The US says it may end its co­operation with Russia over its action in Syria, as Russian airstrikes continue to target civilians.

An air raid on the rebel-­held eastern half of the Syrian city of Aleppo has hit the area's largest hospital for the second time in days, according to medical charity The Syrian American Medical Society.

The facility was struck by barrel bombs, it said. The same facility had been hit in a similar attack on Wednesday. Russian and Syrian air forces resumed attacks on the rebel­held east of the city after a partial truce lapsed on 19 September.

Reports of Russian-­backed Syrian government forces hitting Aleppo's historic Old City continued this afternoon with government troops and rebel forces clashing on the ground in several neighbourhoods in the city. Once Syria's commercial and industrial hub, Aleppo has been divided roughly in two since 2012. The UN says at least 400 civilians, including many children, have been killed in the city this week as a result of Russian and Syrian government attacks.

Government forces have also launched a ground offensive against the rebels. The mounting civilian death toll has caused consternation amongst the international community. The US accuses Russia of driving moderate rebels into the arms of jihadists.

Washington and Moscow have continued to argue over Syria, with the US dismissing Russian accusations that it was protecting a jihadist group in its bid to oust Syrian President Bashar al Assad.

Russian Foreign Minister Sergei Lavrov said the US had broken its promise to separate the powerful Jabhat Fateh al­Sham (previously called the al­Nusra Front) and other extremist groups from more moderate rebels.

State department spokesman Mark Toner said the Russian allegations were "absurd". He told reporters the US had not targeted al­Nusra for months because they had become "intermingled" with other groups and civilians.