ANKARA - Russian President Vladimir Putin on Wednesday informed his Turkish counterpart Recep Tayyip Erdogan of Syrian President Bashar al-Assad's surprise visit to Moscow, Turkish presidential sources said.

Over a phone call, Erdogan expressed his concern over an expected refugee influx following Russia's airstrikes in Syria, the sources added.

The sources said Erdogan underlined during the call that Turkey attaches to fighting all terrorist groups, including the Islamic State (IS), pointing out to links between the Syrian Kurdish YPG militia and the outlawed Kurdish Workers' Party (PKK), who have fought a decades-old insurgency against Turkey.

Assad visited Moscow on Tuesday for talks with his Russian counterpart Putin, Kremlin spokesman Dmitry Peskov said in Moscow Wednesday.

"The president of Syria paid a working visit to Moscow on Oct. 20. Talks in narrow and expanded format with the participation of senior leadership of Russia were held in the Kremlin," he said in a statement.

Putin said Russia is ready to cooperate with other world powers and countries in the region that are interested in a peaceful resolution to the conflict to provide support to the political settlement in Syria.

"We are ready to contribute as much as we can not only to the military action against terrorism, but also to the political process," Putin said in a statement released on the Kremlin website.

Assad, for his part, thanked Russia for preventing the spread of terrorism in Syria to an even larger area and not allowing the situation to develop into a more tragic scenario.(Xinhua)