ASTANA, Kazakhstan: Key power brokers were scrambling on Friday over plans to speed up a political settlement in Syria, with UN envoy Staffan de Mistura joining a second day of talks after negotiations in Moscow.

A new round of peace talks backed by Russia, Iran and Turkey began in the Kazakh capital Astana on Thursday in an attempt to revive a hobbled peace process.

The second day of the talks coincides with the anniversary of a devastating and strategically crucial victory by Syrian forces in Aleppo, the country’s second-largest city and once a rebel stronghold, after a blistering Russian-backed offensive.

The Kremlin is hoping to convert its game-changing military intervention in Syria into a political settlement on its terms, and wants to bring together regime officials and the opposition for a “peace congress” at the Black Sea resort of Sochi.

The Kremlin’s chief negotiator Aleksandr Lavrentyev said on Thursday that “quite a lot of time” at the talks had been spent on Moscow’s proposal for a “Congress of National Dialogue”, and the issue was likely to feature high on the agenda on Friday as well.

But while both Russian officials and regime leader Bashar Al Assad have spoken enthusiastically of the plan, rebel delegates are wary and the UN has yet to endorse the plan.

De Mistura, who held talks with Russian Foreign Minister Sergei Lavrov and Defence Minister Sergei Shoigu in Moscow on Thursday, had said that negotiations over a political settlement should proceed “one step at a time”.

He acknowledged that the most recent round of talks chaired by the UN in Geneva this month — the eighth — “was not a good meeting” as tensions between government and rebel delegations boiled over.

The Syrian regime’s top negotiator, Bashar Al Jaafari, strongly criticised de Mistura after he called for new elections in the war-torn country.

Syria’s opposition said Thursday that it was more important “than ever before” that Russia push Al Assad’s government towards a political settlement.

The Syrian regime and opposition forces are locked in discussions over the reinforcement of the ceasefire, especially in the so-called de-escalation zones, as well as the lifting of sieges on all towns and villages and the delivery of assistance to those in need.

But the opposition said on Friday that the “most important issue for us is the detainee issue.”

“We need to reach an agreement on detainees, which will be the essential core of this round,” Ahmad Tohmeh, head of the rebel delegation, told Turkish officials, according to a statement.

Since the start of Syria’s war in 2011, several diplomatic attempts to halt the conflict have stumbled, mainly over Al Assad’s future.

A fragile ceasefire brokered at the end of last year by Moscow and Ankara has been bolstered somewhat by the negotiations in Astana, where the most recent rounds of talks have focused on implementing four de-escalation zones to stem fighting between regime and rebel forces.

But both Damascus and the rebel factions have regularly accused one another of violating the ceasefire the zones were intended to bolster.

The Astana talks have run in parallel to the negotiations taking place in Geneva with the backing of the United Nations, but both sets of negotiations did not bear much fruit.

Representatives of the opposition have expressed fears the Sochi congress being promoted by Moscow could prove a distraction from the UN negotiations.

Since the victory over Aleppo, Damascus has consolidated control over much of the country, wresting territory from extremist factions not party to the truce, particularly Daesh.

The war in Syria has left more than 340,000 people dead, according to the Syrian Observatory for Human Rights.