Turkey will extend an invitation to Syrian President Bashar al-Assad "any time" for possible talks to restore relations between the two neighbors, Turkish President Recep Tayyip Erdogan said on Sunday.

"We will extend our invitation (to Assad); with this invitation, we want to restore Turkey-Syria relations to the same level as in the past. Our invitation may be extended at any time," Erdogan said, according to a presidency readout of an interview by Turkish media, Reuters reported.

Turkey severed ties with Syria in 2011 after the outbreak of the Syrian foreign-backed militancy in which it supported militants looking to oust Assad.

Speaking to reporters on his flight back from Berlin, Erdogan also said Ankara would reciprocate any positive steps from Damascus, and that Russia's President Vladimir Putin and Iraqi Prime Minister could contribute to facilitating the contact.

"We have now arrived at a point where if Bashar Assad takes a step towards improving relations with Turkey, we will also show that approach towards him," Erdogan said.

"Putin and the Iraqi prime minister have an approach for talks to be in Turkey. We are talking about mediation everywhere, why not with our neighbor?" he was quoted as saying by the Turkish presidency.

Syrian officials have repeatedly said that any normalization in ties can only come after Turkey agrees to pull out thousands of troops from the militant-held northwest.