Russia said Tuesday its warplanes flew out of an Iranian airbase for the first time to bomb jihadist groups in Syria, as fighting raged for control of the ravaged city of Aleppo.
The deployment marks a major switch in the bombing campaign the Kremlin launched in September to support Syrian leader Bashar al-Assad, as until now Moscow had only flown raids out of its bases in Syria and Russia.
Russia\’s defence ministry said long-range bombers and fighter jets took off from the Hamedan base in western Iran and "conducted a group air strike against targets of the Islamic State and Jabhat al-Nusra terrorist groups in the provinces of Aleppo, Deir Ezzor and Idlib".
The strikes destroyed jihadist targets including weapons depots and command centres, "killing a large number of fighters," Moscow said.
The Syrian Observatory for Human Rights said air raids on Tuesday against two rebel-held districts in Syria\’s second city of Aleppo killed 19 civilians.
Observatory head Rami Abdel Rahman said the strikes on Tariq al-Bab and Al-Sakhur, which left three children among the dead, were carried out by either Russian or regime aircraft and had also wounded dozens of people.
Fighting for control of the shattered city, a former economic hub in northwestern Syria, has intensified after regime troops seized control of the last supply route into rebel-held areas in mid-July.
An AFP correspondent in eastern districts of Aleppo said there were heavy air strikes throughout Monday night and into the day on Tuesday in Tariq al-Bab and Al-Sakhur.
Men were seen pulling debris and rubble from the ground floor of a building, while others zipped corpses into black body bags.
The increased fighting has raised concerns for the estimated 1.5 million civilians still in Aleppo, including some 250,000 in rebel-held areas.
Since mid-2012, Aleppo has been divided between opposition control in the east and government forces in the west, with both sides exchanging accusations of indiscriminate attacks against civilians.
The UN Commission of Inquiry on Syria said in a statement it was "gravely concerned for the safety of civilians" in Aleppo and called for "immediate attention and response" to their plight.
Human Rights Watch accused Syrian and Russian warplanes of having repeatedly used incendiary weapons against civilians in northern Syria, saying it had documented their use at least 18 times since June.
Iran and Russia are the two firmest backers of the Assad regime, with Tehran commanding thousands of troops fighting for him on the ground as Russia provides airpower.
Both oppose calls for Assad to step down in a bid to resolve the conflict that has killed more than 290,000 people since it erupted in March 2011.
Moscow has so far used warplanes stationed at its Hmeimim airbase outside the Syrian coastal city of Latakia, as well as ships in the Caspian Sea and a submarine in the Mediterranean, to bombard Syrian territory.
But Hmeimim — which a senior Russian official said recently Moscow is looking to expand into a permanent facility — is home to only short-range planes and fighter jets, meaning long-range bombers had to be deployed from southern Russia.
The use of the Iran base could help boost Moscow\’s firepower by cutting the time it takes for its jets to reach their targets, military analyst Pavel Felgenhauer told AFP.
"Bombers can transport more bombs if their flight time is short," he said.
Ali Shamkhani, secretary of Iran\’s Supreme National Security Council, told state news agency IRNA that Moscow and Tehran "exchange capacities and facilities" in the fight against terrorism in Syria.
An unnamed military source told Interfax news agency on Monday that Russia had also sent requests to Iran and Iraq to fire cruise missiles across their airspace.
Russian deputy foreign minister Mikhail Bogdanov was in Tehran on Monday, where he discussed the "high mutual interest" of deeper cooperation between Russia and Iran in the Middle East, his ministry said.
Defence Minister Sergei Shoigu has held several meetings over the past year with Iranian counterpart General Hossein Dehghan, most recently in June in Tehran, where they pledged to deliver a "decisive" battle against "all terrorist groups".
Shoigu also said in comments aired Monday that Russia and the United States were close to joining forces in some form around Aleppo.
But US State Department spokeswoman Elizabeth Trudeau refused to confirm any collaboration.
A senior Russian diplomat in Geneva, Alexei Borodavkin, told Interfax on Monday that the Russian and American militaries were in the process of "agreeing some concrete practical issues" regarding humanitarian aid deliveries to the city.