Moscow will host the leaders of Russia, Iran and Turkey early next year to discuss the Syrian conflict, Russia's deputy foreign minister said on Friday, after the United States announced it was withdrawing troops from the country.

“It's our turn to host the summit... around the first week of the year. This will depend on the schedules of the presidents,” Mikhail Bogdanov was cited as saying by Interfax news agency.

The meeting will be the latest step in the Astana peace process set up in early 2017 by Russia and Iran, who support President Bashar al-Assad's regime in Syria, and opposition backer Turkey.

The Astana process was launched after Russia's military intervention in Syria tipped the balance in the Damascus regime's favour. It has gradually eclipsed an earlier United Nations-sponsored negotiations framework known as the Geneva process.

The last meeting between Russia's Vladimir Putin, Iran's Hassan Rouhani and Turkey's Recep Tayyip Erdogan took place in Iran in September with the fate of the rebel-held Idlib province dominating the agenda.

US President Donald Trump in a shock announcement recently said he was pulling out some 2,000 American soldiers from Syria, claiming the militant Islamic State group's terrorists had been defeated.