Veteran envoy Staffan de Mistura says he hopes to invite the Syrian regime and opposition groups back to Geneva later this month for a new round of talks, which will include the issue of counter-terrorism at the request of Damascus.
UN peace talks, aimed at ending the Syrian war have ended without reaching a solution for the conflict.
The talks, that included a delegation representing the Syrian regime of Bashar al Assad and three opposition groups, were the first to be held in more than a year.
But the UN says the latest talks ended on a more positive note than the previous meetings with the Syrian regime and opposition having agreed upon a "clear agenda" to seek to end the country's six-year-old war.
Veteran envoy Staffan de Mistura said he hopes to invite both sides back to Geneva later this month for a new round of talks, which will include the issue of counter-terrorism at the request of Damascus.
"The train is ready, it is in the station, it is warming up the engine. Everything is ready, it just needs an accelerator," he said at the end of nine days of talks in the Swiss city.
Talks in Astana, convened by Russia, Turkey and Iran, would be complementary and deal with "maintenance of the ceasefire, immediate confidence-building measures and operational counter-terrorism issuees", he told a final press conference.
He said he felt "comfortable" that all sides could "live with" the Geneva agenda.
"I believe that we have a clear agenda now in front of us," he told reporters, adding: "We did discuss procedure, .. but we also discussed substance."
The Geneva negotiations, the first since April 2016, were the latest effort to seek to end a conflict that began in March 2011 with protests against Syrian regime leader Bashar al Assad. Its seventh year begins on March 15.
Since then more than 310,000 people have been killed and hundreds of thousands have fled the country, fuelling instability in neighbouring countries and creating Europe's biggest migrant crisis since World War II.
The warring Syrian sides have been joined in Geneva by envoys of key parties including notably Russia, a major ally of Damascus.