GENEVA, Dec. 17 (Xinhua) -- The United Nations Special Envoy for Syria Staffan de Mistura is expected to host a joint meeting Tuesday at the Palais des Nations in Geneva with high-level representatives from Iran, Russia and Turkey, his office said on Monday.

A source with the UN Envoy's office said the efforts to establish a "credible, balanced and inclusive constitutional committee" have been the subject of continuing consultations.

Media reports said a list of members of the Syrian Constitutional Committee is ready and will be handed over to de Mistura this week.

The formation of the constitutional committee was agreed upon in January during inter-Syrian talks, brokered by Russia, Iran and Turkey, in Russia's Sochi.

The committee is expected to have 150 members from both the Syrian government and the opposition.

On Dec. 20 the UN envoy will addresses the Security Council in New York for the last time before he steps down on the last day of this year.

UN Secretary-General Antonio Guterres has appointed, Geir Pedersen, who is Norway's ambassador to China, to succeed de Mistura on Jan. 1 next year.