FNA- UN Special Envoy for Syria Staffan de Mistura will visit Tehran later in the day to meet with Iranian Foreign Minister Mohammad Javad Zarif and other officials, a ministry source said on Sunday.

De Mistura is also expected to meet with Iranian Deputy Foreign Minister for Arab and African Affairs Hussein Jaber Ansari as well as the Iranian team on Syrian settlement talks, the source told Sputnik.

The next round of the Geneva talks on Syrian settlement is scheduled for September, following a new high-level meeting on Syria in Astana which is set to take place late August.

In May, Iran, Russia and Turkey � the three guarantor states of the Syrian ceasefire regime � signed during the Syrian settlement talks in Astana a memorandum on the establishment of de-escalation zones. It stipulated the creation of four de-escalation zones., and the guarantors have reached agreements with Syrian opposition groups to set up three zones, with the consultations continuing on the fourth safe zone in the Idlib province.

Syria has been engulfed in a civil war for over six years with the government troops fighting against numerous opposition factions as well as terrorist groups such as Daesh and the Jabhat Fatah al Sham, both outlawed in Russia.