Russia has warned the US not to take any action against the Syrian regime even as the largest hospital in rebel-held eastern Aleppo was bombed on Saturday (1 October).

Russia's foreign ministry spokesperson Maria Zakharova was quoted by the state- run Sputnik news agency as saying: "If the US launches a direct aggression against Damascus and the Syrian army, it will lead to terrible, tectonic shifts not only on the territory of this country but also in the region in general."

She added that the US risked creating a power vacuum if it were to overthrow Syrian President Bashar al-Assad with a power vacuum being filled by "terrorists of all sorts".

Meanwhile, US Secretary of State John Kerry, in a meeting with a group of Syrian civilians last week—which took place on the sidelines of the United Nations General Assembly in New York—supported their demand for more decisive US action amid the Syrian offensive backed by Russia, according to an audio recording obtained by CNN.

Kerry is heard saying in the audio: "I've argued for the use of force. I'm the guy who stood up and announced that we're going to attack Assad for the use of weapons." He was referring to the discussions within the Obama administration when Assad allegedly deployed chemical weapons in 2013.

In another audio recording published by the New York Times, Kerry can be heard venting his frustrations: "We are trying to pursue the diplomacy and I understand it's frustrating. You have no one more frustrated than we are."

The Syrian offensive which began on 22 September has seen dozens of civilians killed and buildings flattened in eastern Aleppo. An estimated 250,000 people live in the area under a government siege. Diplomatic efforts to put an end to the fighting have collapsed.

The Russian foreign ministry stated on its Facebook page that Foreign Minister Sergei Lavrov spoke on the phone to his US counterpart Kerry on Saturday, adding that they "examined the situation in Syria, including the possibility of normalising the situation around Aleppo". The latest attack on the hospital also comes on the first anniversary of the Russian intervention.

Syrian regime bombs hospital
A damaged field hospital room is seen after airstrikes in a rebel-held area in Aleppo, Syria REUTERS/Abdalrhman Ismail