Turkey on Saturday said that Syrian President Bashar al-Assad should leave office "at some point" in the future but denied there was any kind of contact between Ankara and Damascus over ending the seven year civil war.
Ankara has been a prime foe of Assad throughout the conflict but has occasionally softened its rhetoric in the last months as Turkey strengthened cooperation with the regime's main ally Russia.
President Recep Tayyip Erdogan's spokesperson, Ibrahim Kalin, told journalists in Istanbul that Assad was not the leader to unite Syria and had lost legitimacy.
But Kalin said there needed to be a "political transition in Syria", leading to a new constitution and elections.
"It is not going to be easy but that's the ultimate goal to reach and at some point Assad will have to go," he added.
"Where exactly, at what point precisely (Assad leaves), is something that will be answered as we go on, obviously," he said.
He was speaking after Russia on Tuesday hosted a peace congress on Syria, with both Russian President Vladimir Putin and Erdogan expressing "satisfaction", according to the Kremlin.
Kalin, who is also regarded as Erdogan's top foreign policy advisor, also indicated that Turkey believed Russia's priority was ensuring Syria did not become a failed state, rather than concern about Assad himself.
He said the Russian position has been "not so much protecting Assad personally but protecting the state institutions, state apparatus and the Syrian army and the regime elements".
He said: "They want to make sure that the state doesn't collapse completely in Syria."
Turkey's position on Assad has been under ever greater scrutiny since Ankara on January 20 began a cross-border operation with Syrian allied rebel forces against Kurdish militia based in the town of Afrin.
The main opposition Republican People's Party (CHP) leader Kemal Kilicdaroglu has called for Ankara to make contact with the Damascus regime as the best way of ensuring Syria's territorial integrity.
But Kalin denied any contact with Damascus "at any level".
"There is no communication, no relationship, direct (or) indirect. Nothing with the Syrian regime, at any level. I can say that categorically and very clearly," he said.
He also rejected the notion that there had been any agreement with Russia allowing the Afrin operation to go ahead in exchange for a deal over the rebel-held neighbouring region of Idlib.
"There's no deal with Russia 'you give Idlib and take Afrin'... they are two separate operations," he said.
Kalin indicated that Turkey's position on Syria was less well aligned with the other major ally of the Damascus regime, Iran.
"Iran supports the regime but we don't, and they want to keep Assad the person and we don't," said Kalin, noting that Tehran had "clear leverage" over the Damascus regime.