Hussein Aoghlam, the Iranian Foreign Ministry’s spokesman, told AFP it had a “mutual understanding” with Turkey over the downing of the Su-24, but that it had no immediate comment on the latest developments.

But the Turkish government said that it had no intention of opening a diplomatic channel with the Iranian government, despite Turkey being a long-time supporter of Assad.

Syria’s regime of President Bashar al-Assad has often used Iranian-made helicopters to drop barrel bombs on civilian areas in opposition-held territory.

In a joint statement the Syrian opposition had accused “the Turkish military for targeting a convoy of humanitarian corridors and hospitals in the suburbs of Aleppo”, but added that “Iran provided the Syrian Army with help to take control of Idlib”.

Syria’s military command also said Iranian-made helicopters had been deployed in Syria for medical missions.

“An Iranian-made AH-64 chopper took part in the liberation of the town of Jarablus,” the military command said. A military source in Homs said Tehran’s cooperation has been “firm for the last three years”.

The Syrian army said its forces had launched an operation to “clean the countryside of all terrorists and civilians, including the terrorists.”

On Monday, UN human rights chief Zeid Ra’ad Al Hussein called on President Bashar al-Assad to stop the use of “massacres and other crimes” against his people while he attempts to maintain the regime’s grip on power.

Russia and China have blocked similar UN Security Council measures in the past.

The UN has said that up to 4,000 people have been killed in the conflict, with the Syrian Observatory for Human Rights and the Syrian Network for Human Rights estimating that 6,400 people have been killed since the uprising began in March 2011.

The Geneva peace talks ended in deadlock just days before the UN was due to meet to discuss Syria’s future.

But a Russian proposal to postpone the talks to coincide with a meeting between Assad and his main foreign backers and the opposition in Kazakhstan, appeared to be shelved by Russia and China despite concerns from the West and some Arab states over the risks of a further escalation in bloodshed.

“We will have a meeting of the foreign ministers of Russia, China, the United States, United Kingdom, France, Germany, Iran, Turkey and Qatar within six days, and then we will continue our work