Bashar al-Jaafari, the head of the delegation representing Syrian President Bashar al-Assad, attends a news conference following Syria peace talks in Astana, Kazakhstan January 24, 2017.

A third round of Russian-backed talks on the Syrian war opened in the Kazakh capital Astana on Tuesday without armed rebel groups, leaving little hope for a breakthrough in ending the six-year conflict.

The talks, sponsored by regime allies Russia and Iran and Turkey, come as other diplomatic efforts to end the bloodshed have proved fruitless.

Regime negotiator Bashar al-Jaafari, Syria’s ambassador to the UN, slammed the decision by the rebels to snub the talks but insisted that progress could still be made in their absence.

“We are eager to ensure the success of the Astana path… whether or not the armed factions attend,” Jaafari was quoted as saying by Syria’s SANA news agency. “The failure of the armed factions to attend Astana shows the indecency of their politics.”

Jaafari said the regime delegation had come to Astana primarily to meet with Russia and Iran, and not armed opposition groups. He said that the sides would discuss “separating the opposition from the terrorists”, SANA reported.

Previous rounds of talks in Astana were focused on bolstering a frail nationwide truce brokered by Moscow and Ankara in December that has been jeopardized by fighting across swathes of Syria.

A Syrian rebel spokesman on Monday said the delegation was skipping the Astana talks because of the regime’s “unfulfilled pledges related to the cessation of hostilities”.

Kremlin spokesman Dmitry Peskov told reporters on Tuesday that the Astana talks were “from time to time truly complicated by the existing differences in the different sides’ approaches”.

A new round of negotiations in Geneva is set to begin on March 23 and will focus on governance, the constitution, elections, counter-terrorism and possibly reconstruction, according to the UN’s Syria envoy Staffan de Mistura.