Russian President Vladimir Putin greets his Syrian counterpart Bashar al-Assad during a meeting at the Kremlin in Moscow on October 20, 2015. (AFP)
Russian President Vladimir Putin and Turkish leader Recep Tayyip Erdogan have discussed the surprise visit to Moscow of Syria's embattled President Bashar al-Assad by telephone, the Kremlin said today.
"The situation in Syria has been discussed," Kremlin spokesman Dmitry Peskov was quoted as saying by Russian news agencies.
"In this context the leader of Russia informed his Turkish counterpart about the results of Syrian President Assad's visit to Moscow."
The Turkish presidency confirmed the phone call.
Turkish news agency Anatolia said Erdogan had expressed concern over the situation in Syria, adding that the two leaders were set to hold a meeting at a Group of 20 gathering in Antalya, Turkey next month.
Erdogan also warned Putin that an offensive in Aleppo could cause a "new wave of refugees," the Anatolia news agency reported.
On Friday, Syrian regime forces began a new push south of the city.
More than 250,000 people have already been killed and millions forced from their homes by the conflict, sparking a mass migration of refugees that has raised tensions in Europe.
Moscow has been supporting Assad's regime since the start of the conflict in 2011, while Erdogan has been one of Assad's most vocal opponents.
Moscow launched a controversial bombing campaign in Syria on September 30, saying it needed to target Islamic State jihadists before they cross the border into Russia.
But the West has accused Russia of propping up Assad and also targeting Western-backed moderate rebel groups.
Turkish Prime Minister Ahmet Davutoglu said earlier Wednesday that any political transition period in Syria must be part of a "formula" which guarantees Assad's departure as soon as possible.
"The focus should not be on a transition period with Assad, but on a formula that will see him go and such formula should be implemented as soon as possible," he told reporters.
Turkey backed Assad's regime until the outbreak of the civil war in 2011, after which it switched its support to rebels fighting to overthrow him.
Since then it has insisted the Syrian president must go.
Last month Erdogan suggested for the first time that Assad could be part of a future transition.