Syrian government and opposition representatives had been "serious and engaged" during the latest nine days of talks in Geneva, UN mediator Staffan de Mistura told reporters.
He said all sides were "keen and ready to return to Geneva for a sixth round of talks," adding that he would announce the date after discussions next week with UN chief Antonio Guterres and the UN Security Council.
The two sides, who met with de Mistura separately, did finally delve into some substance, after spending four previous rounds squabbling over the agenda.
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They began discussing four separate "baskets" of issues, on governance, drafting a new constitution, elections and combating terrorism in the war-ravaged country.
There was never much hope of a breakthrough, with the sides hopelessly deadlocked over the fate of President Bashar al-Assad and violence persisting in a six-year conflict that has already claimed more than 320,000 lives.
De Mistura previously warned not to expect "miracles" and on Friday hailed the fact that no one had walked out. He acknowledged though that the talks still remained in the preparation stage.
No immediate peace deal
"In every negotiation there are certain issues that need to be prepared... before the real, real peace negotiations start... and it is clear, we are not quite there," he said.
"I cannot deny that there are serious challenges, and I am not seeing immediately this developing into a peace agreement," he added.
He insisted that "we must maintain this incremental momentum on the political process, even if it is only incremental."
The negotiating sides hailed that negotiations on substance had finally begun, but appeared less optimistic than their mediator that progress was being made.
Nasr al-Hariri, the chief negotiator for the opposition High Negotiations Committee (HNC), lamented to reporters that the opposition was dealing with "a side that does not want to reach a political solution."
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The chief negotiator on the government side, Syria's ambassador to the UN Bashar al-Jaafari, was even more pessimistic.
"We were looking forward to achieving... at least some progress in this round, but this did not happen," he told reporters.
He maintained that his opponents "do not want a political solution, unless [it] is in accordance with their illusions... that we would hand over the keys to Syria to them."
The Syrian government appears to have little reason to make concessions.
The rebels increasingly find themselves on the back foot, both on the ground, where they have been haemorrhaging territory, and when it comes to international support.
The United States, long the opposition's most powerful backer, acknowledged Thursday that it is no longer focused on ousting Assad as it seeks a new strategy to end Syria's civil war.
Other opposition backers have been indicating the same, even as government supporters Russia and Iran wield increasing influence.
De Mistura on Friday meanwhile dismissed a barrage of rumours he was preparing to step down.
Only "if and when you will hear it directly either from the Secretary General or from myself, then you have to take it very seriously," he told reporters.
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