The delegations will hold expert-level meeting on Syrian settlement today before the main talks due on May 3-4.
Syria's armed opposition groups have announced readiness to take part in the 4th round of talks in Astana.
Earlier this year, Astana hosted three rounds of high-level talks to end the military confrontation in Syria. It brought together representatives of the three guarantor states - Russia, Turkey, and Iran, as well as the Syrian government and armed opposition, along with representatives of the UN, the United States and Jordan.
The first round took place on January 23-24 and gathered together representatives of the Syrian armed opposition and government for the first time.
The second round took place on February 15-16 and resulted in the agreement of the participants to set up a ceasefire monitoring group, encompassing Iran, Russia and Turkey, that would report to the United Nations.
Astana hosted the third round on March 14-15, however without participation of Syrian armed opposition.
LR/PR