The leaders of Russia, Turkey, France and Germany have called for a lasting ceasefire in Syria following violence in last remaining major rebel stronghold.
A constitutional committee should meet by the end of the year, the leaders of the four countries, who gathered for a summit in Istanbul, said.
Ankara, which supports the rebels seeking to overthrow president Bashar al-Assad, and Moscow, Assad's key foreign ally, recently brokered a deal to create a demilitarised zone in Syria’s Idlib region.
French President Emmanuel Macron told reporters that the international community would be watching to make sure that Russia and Turkey respect the agreement they have negotiated.
Speaking after the four-way summit on Saturday, he said: "We will all be extremely vigilant to ensure that these commitments are met and that the ceasefire is stable and sustainable.
"We are counting on Russia to exert a very clear pressure on the (Syrian) regime which very clearly owes it its survival."
Under their deal last month, Turkey and Russia agreed to create a buffer zone around Idlib amid fears of an impending assault on the northwestern province.
On Friday, shelling in Idlib killed at least seven civilians – the largest one-day loss of life there since Russian air strikes stopped in mid-August.
Russian President Vladimir Putin said Turkey was fulfilling its obligation regarding the agreement on Idlib. The process was not easy and Russia plans to continue cooperating, he said.
In a joint statement, Macron, Putin, Turkish President Tayyip Erdogan and German Chancellor Angela Merkel also called for a committee to be established to draft a new Syrian constitution.
Mr Erdogan told reporters that should be done "as soon as possible", adding he hoped it would be before the end of the year.
Additional reporting by Reuters
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