Staffan de Mistura will hold high-level talks next week to work on setting up a constitutional committee, the UN said.

The United Nations Special Envoy for Syria Staffan de Mistura will hold talks with high-level officials from Iran, Russia and Turkey in Geneva early next week on setting up a constitutional committee, a UN statement says.

The talks on forming a “credible, balanced, and inclusive” committee to draft a new constitution for Syria and usher in elections will take place before de Mistura’s monthly presentation to the UN Security Council set for December 20, a UN statement said on Friday.

Last month, Syria’s warring sides and mediators meeting in Kazakhstan failed to agree on the formation of a constitutional committee which is key to ending the seven-year civil war. De Mistura, whose term ends at the end of the year, called it a “missed opportunity”.

At issue is the 50-member delegation comprising Syrian experts, civil society, independents, tribal leaders and women that de Mistura was authorised to put together by countries attending a Russian-hosted Syrian peace conference in the Black Sea resort of Sochi in January.

An agreement has already been reached on a 50-member government delegation and a delegation equal in size from the opposition for the drafting committee.

Syrian President Bashar al-Assad has said his government will only consider amendments to the current constitution, in defiance of the Sochi agreement to have the government, opposition and independents draft a new document.

Earlier this week, de Mistura said work was still ongoing to form the constitutional committee, adding that if an announcement about the committee is not made, “we will have to draw ourselves some conclusions”.

Syria’s war has killed more than 360,000 people since it started in 2011 with the police crackdown on anti-government protests.

The Syrian government has regained control over the majority of the country’s territory since the Russian military intervened in 2015, backing al-Assad’s government.