"The three rounds of talks were unsuccessful because of the stubbornness of the regime and its continued bombardments and aggressions towards the Syrian people," Mohammad Aloush, a member of the Jaish al-Islam (Army of Islam) rebel group, said via Twitter. "I therefore announce my withdrawal from the delegation and my resignation."
The Syrian opposition had suspended formal participation in the peace talks on April 27, saying they would only return if Syrian army offensives were scaled back.
Geneva talks stalled for now
A new round of talks had been expected for the end of the month, but no new date has been announced and the UN's Syria envoy, Staffan de Mistura, said this week there were no plans for new rounds in the next three weeks.
A joint initiative by Russia and the United States produced a shaky ceasefire agreed to in February between Damascus and non-jihadist rebels. But the negotiated "cessation of hostilities" has been repeatedly violated by all sides.
This comes as the head of the main Syrian opposition delegation Asaad al-Zoubi also told the Saudi al Hadath TV channel that he too wanted to be relieved of his post, but did not confirm he had taken a similar step.
The Syrian conflict has since spiraled into a full blown civil war drawing in Russia, Turkey, Iran and other regional players. The fighting has left some 280,000 dead and driven millions from their homes, many of them trying to reach the relative safety of Europe.
jar/jr (AFP, Reuters)