Putin told Trump of “the main results” of his summit with Assad “at which the Syrian leader confirmed his commitment to the political process, (and) conducting constitutional reform and presidential and parliamentary elections,” the Kremlin said.

During the phone call with Trump the Kremlin stressed Putin mentioned the “need to keep Syria’s sovereignty, independence and territorial integrity intact.”

A political settlement in Syria should be based on principles to be worked out during an all-inclusive “internal negotiating process,” the Kremlin added.

Separately, Putin discussed Syria with the Saudi king, Egyptian President Abdel Fattah al-Sisi and Israeli Prime Minister Benjamin Netanyahu, touting Moscow’s recent initiative to bring Assad’s regime and its opponents together for a “congress.”

Different factions of the Syrian opposition will meet from Wednesday in Riyadh in talks hosted by Saudi Arabia.

The aim of the Saudi-backed High Negotiations Committee is to reach consensus on a strategy for UN-backed talks in Geneva, which will focus on a new constitution for Syria and fresh elections.

Earlier Tuesday, Putin told visiting Czech President Milos Zeman that Assad’s troops controlled more than 98 per cent of territory. “You won in Syria,” Zeman told Putin.

Analysts say that Russia’s decision to intervene militarily in Syria in 2015 appears to have saved Assad’s regime but a peace settlement seems ever more elusive.

Assad’s fate remains a huge stumbling block, preventing global players from reaching a peace settlement over Syria’s six-year war.

Billed as a “working visit”, the meeting between Putin and Assad in Sochi on Monday was their first meeting in two years, after the Syrian leader travelled to Moscow in 2015 to thank Putin for his decision to intervene in Syria.

“As for our joint work in the fight against terrorism in Syria, this military operation is coming to an end,” Putin said in comments released on Tuesday. “Thanks to the Russian army, Syria has been saved as a state. Much has been done to stabilise the situation in Syria.”

Assad said he wanted to advance negotiations.

“We don’t want to look back and we are ready for dialogue with all those who want to come up with a political settlement,” Assad said in translated comments.

Russia’s army chief of general staff, Valery Gerasimov, was quoted by Russian news agencies as saying that “despite the fact that there remains a raft of unresolved problems” the military stage “is coming to its logical conclusion”.

Putin’s Wednesday summit with Turkish President Recep Tayyip Erdogan and Iran’s leader Hassan Rowhani will take place ahead of parallel UN-led talks in Geneva set for November 28.

The meeting comes as Ankara, Moscow and Tehran cooperate with increasing intensity on ending the civil war in Syria that has claimed some 330,000 lives and made millions homeless.

The trio are cooperating despite Turkey still officially being on an opposite side in the Syrian conflict from Russia and Iran.

Russia, Iran and Turkey have backed negotiations in the Kazakh capital Astana that have brought together the representatives of the opposition and the regime.

The talks led to the creation of four so-called “de-escalation zones” that produced a drop in violence, but fighting and bombardments continued.