UN-led peace talks on Syria have been postponed until February 20, the UN special envoy told the Security Council on Tuesday, according to diplomats at the closed meeting.
The talks in Geneva had been scheduled to begin on February 8 but Russian Foreign Minister Sergei Lavrov last week announced they would be delayed, without providing reasons.
UN envoy Staffan de Mistura said the delay would give the Syrian opposition more time to prepare and ensure that the talks are as inclusive as possible, two diplomats told AFP.
Russia, Iran and Turkey last week led talks in the Kazakh capital of Astana on shoring up a ceasefire in Syria, where more than 310,000 people have died in nearly six years of war.
The council met behind closed doors to hear a report from De Mistura on preparations for the Geneva talks amid concerns the Astana discussions could open up a new track of negotiations.
"We have been concerned that the Geneva talks have been delayed and we would be concerned if there were any watering down of the basis of those talks," British Ambassador Matthew Rycroft told reporters ahead of the meeting.
"It's very important that there is confirmation that the UN will lead the next round of talks," said Swedish Ambassador Olof Skoog, this month's council president.
During the Astana talks, Russia, Syria's main ally, presented opposition rebels with a draft constitution that was immediately rejected by the groups.
The unilateral move by Russia raised concern in Western capitals.
"The UN has to be front and center in the political process," said French Ambassador Francois Delattre.
He cited the need to respect the Geneva communique agreed with Russia that calls for a transition in Syria.
"We start with a transition, then the constitution, and then the elections," said Delattre. "I think if we can all stay on this line, then we can move."
Previous UN-led talks have broken down over disagreements on ensuring a transition in Damascus that would lead to President Bashar al-Assad's exit from power.
Western powers have for weeks questioned the purpose of the Astana talks and raised concern that they could sideline the Geneva talks.
Turkey, which backs rebel forces, has for the first time conceded that a peace deal that excludes Assad from power might not be possible.
The new date was announced after US Ambassador Nikki Haley meet with De Mistura on Monday to discuss the way forward in Syria.
Invitations to attend the Geneva talks will be sent out on February 8, De Mistura told the council, according to diplomats.