Staffan de Mistura describes Syria's political transition as the core issue, and as talks are stalling over it, he has urged the US and Russian foreign ministers to give impetus to the peace process.
A Syrian government official said on Wednesday Damascus would respond to a UN proposal on the intra-Syrian peace talks at the start of the next round of negotiations, but did not say what it contained.
The proposal was handed to the Syrian delegation by UN Special Envoy on Syria, Staffan de Mistura, on the penultimate day of peace talks in Geneva. A fragile truce holds in Syria, engineered by Washington and Moscow three weeks ago.
The five-year-old conflict between the government and insurgents has killed more than 250,000 people, allowed ISIS to take control of some eastern areas and caused the world's worst refugee crisis.
"We received a letter that will be studied after we return to Damascus," delegation head Bashar Ja'afari told reporters after meeting de Mistura. "We will respond to it at the beginning of the next round," he said, declining to take any questions.
The talks adjourn today with the next round expected in early April.
Syria's government delegation has so far rejected any discussion of the future of President Bashar al-Assad, who opposition leaders say must go as part any transition.
The UN envoy said on Tuesday that he aimed to establish if there were any points held in common by the different parties. If successful, he would announce these today.
De Mistura, describes Syria's political transition as the core issue, and as talks are stalling over it, he has urged the US and Russian foreign ministers to give impetus to the peace process when they meet in Moscow this week.
The head of the Cairo group of activists Jihad Makdissi, one of the parties in the peace process, told reporters on Wednesday de Mistura was planning to issue a paper on a potential "common vision" for Syria.
Makdissi said he believed de Mistura's paper was on the right path.
"It covers many points important to the Riyadh platform, the Cairo platform, and the Moscow platforms," he said, referring to different activists and opposition groups.
The cessation of hostilities deal, not signed by any of the warring parties, remains fragile and diplomats are concerned that, after more than a week of talks, it is at risk of collapsing unless headway on the matter of political transition is made soon.
Asaad al-Zoubi, head of the main opposition council's delegation, said on Tuesday it was "obvious" there were no points of convergence with the Syrian government and accused it of renewing sieges and barrel bombing campaigns against civilians.
The UN humanitarian advisor on Syria Jan Egeland told reporters that the UN had received the green light for eight or nine of the 11 areas it had asked to deliver aid to, including three or four besieged areas.
However, the UN had not been given permission to access the towns of Daraya, where the World Food Programme has said some people have been reduced to eating grass, or Douma. Both are close to Damascus.
He also said a local agreement to end the siege of al Waer of Homs city had broken down, and that the UN would need to mediate.
"Indeed there are new areas of great concern," he said.
© Thomson Reuters 2016