Staffan de Mistura's dire assessment -- and a rare admission of failure -- came at the end of the eighth round of the largely ineffective, UN-sponsored talks in Switzerland.
The UN envoy said he was "disappointed," after going in with ambitions to get the two sides to talk to each other.
De Mistura also offered some of his harshest criticism yet of the Syrian government delegation, accusing it of setting preconditions that he had warned against, and said its team refused to discuss anything other than "terrorism" -- a term the government uses to refer to all armed opposition against President Bashar Assad.
De Mistura said the opposition was engaged on other subjects, such as governance, the constitution and elections.
Also Read
"It is a big missed opportunity, a golden opportunity missed at the end of this year," he said.
Asked whether there was any point in returning to Geneva, de Mistura said the alternative would be abandoning Syria and a return to war.
"Our motto is never give up," he said.
The head of Syria's government team in Geneva, Bashar Ja'afari, extinguished any hopes of a last-minute breakthrough when he emerged earlier yesterday from a meeting with de Mistura to say his team would not talk to the opposition as long as it insists on Assad's removal from power.
The communique stated that the opposition's ultimate goal was to see Assad step down at the start of a political process.
The Damascus official described the statement as "blackmail of the Geneva process" and said its withdrawal was a precondition for talks. He also told reporters in Geneva that "those who drew up the Riyadh communique are the ones who sabotaged this round" of talks.
Earlier today, de Mistura called on Russian President Vladimir Putin to "have the courage" to push his Syrian government allies to accept new elections and a new constitution.
Russia has provided crucial military and diplomatic backing to Assad's forces, though Putin announced a drawdown of his forces in Syria during a surprise visit to the Mideast country on Monday.
The Russian president touched down at a Russian military base in Syria in the wake of battlefield successes to laud the troops' achievements and tell them that a significant number would be going home.
"Peace must be won -- and for the peace to be won, it's necessary to have the courage to push the government also to accept that there must be a new constitution and new elections," the UN envoy added in comments late Wednesday to Swiss broadcaster RTS.
Ja'afari also blasted de Mistura for his comments on Russia, saying such positions "derail his mandate as a facilitator of the talks, which will have an impact on the Geneva process all together.
In the interview, de Mistura said it was "regrettable" that Assad's delegation had refused to meet face-to-face with the opposition. At the start of the latest round, the delegations at one point were just meters (yards) away from one another in separate rooms.
Hinting at his repeated concerns about a de facto partition of Syria, the UN envoy held up a color-coded map showing the divisions of territorial control in Syria.
The war is estimated to have killed at least 400,000 people and driven over 12 million from their homes. De Mistura's two predecessors stepped down in frustration after failing to jumpstart peace talks.
Disclaimer: No Business Standard Journalist was involved in creation of this content