The United States has suspended talks with Russia on trying to end the violence in Syria, accusing Moscow of not living up to its commitments under a ceasefire agreement.

US Secretary of State John Kerry threatened last week to end the talks after warplanes believed to belong to Russia bombed a UN aid convoy.

The confirmation that the US-Russian talks have now collapsed suggests there is little hope of a diplomatic solution to end the five-and-a-half-year-old civil war anytime soon.

The announcement came as Syrian government forces supported by Iranian-backed militias and Russian air power pounded the rebel-held area of Aleppo.

The largest trauma hospital in eastern Aleppo was hit again by several airstrikes on Monday, completely destroying the facility and killing three maintenance workers who were repairing it after an earlier attack.

In opposition-held Hama province, another hospital became inoperable after a suspected Russian bunker buster bomb hit the facility.

“The United States is suspending its participation in bilateral channels with Russia that were established to sustain the cessation of hostilities,” US State Department spokesman John Kirby said in a statement.

“This is not a decision that was taken lightly.”

An injured Syrian man arrives on a stretcher to receive treatment at a makeshift hospital on Monday in Aleppo. Photo: Getty.

‘US to continue communication with Russian military’

It could also trigger deeper US consideration of military options such as providing more sophisticated arms, logistical support, and training to Syrian rebel groups that US officials have said were under consideration, either directly or via Gulf Arab states or Turkey.

However, US President Barack Obama has been loath to get the United States more deeply involved in a third war in the Islamic world and US officials have said he is unlikely to do so with less than four months left in office.

In the statement, Mr Kirby said the United States would continue to communicate with Russian military to avoid so-called de-confliction — to avoid accidental military interactions — over Syria.

But he said the United States would withdraw all personnel it had dispatched to prepare for military co-operation with Russia under the latest ceasefire agreement.

“Unfortunately, Russia failed to live up to its own commitments … and was also either unwilling or unable to ensure Syrian regime adherence to the arrangements to which Moscow agreed.”

News of suspending the talks came as diplomats said the United Nations Security Council would begin to negotiate on Monday a draft resolution that urges Russia and the United States to ensure an immediate truce in Aleppo.

United Nations Syria envoy Staffan de Mistura said he “deeply regrets” the suspension, but said the world body would “continue to push energetically for a political solution” to end the war.

“The UN will never abandon the Syrian people to a destiny of endless violent conflict,” Mr de Mistura’s office said in a statement.

– ABC