Staffan de Mistura
Staffan de MisturaReuters

Elections in Syria observed by the United Nations should be held in 18 months, the UN's Syria envoy Staffan de Mistura told Russia's RIA Novosti state news agency on Friday.

"New elections...should be held 18 months from the start of talks, that is from March 14. The elections, both presidential and parliamentary, will be under UN observation," de Mistura said in an interview translated into Russian.

The latest round of negotiations aimed at ending Syria's war are to begin on Monday.

The UN envoy said the first question on the agenda was "an inclusive new government" followed by a new constitution and elections.

"I hope that during the first stage of talks, we reach progress at least on the first question," de Mistura was quoted as saying.

A great stumbling block in the negotiations is to be the fate of Bashar al-Assad. Since last September Russia has been propping up Assad's regime with airstrikes.

Russia's foreign minister on Friday urged the UN's special envoy on Syria to include Kurds in upcoming talks that aim to resolve the five-year Syrian civil war.

"Launching negotiations without the participation of this group would be a sign of weakness from the international community," Sergei Lavrov told reporters at a joint news conference with his Chinese counterpart.

AFP contributed to this report.