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 on Wednesday.

"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."