Iranian Foreign Minister Javad Zarif arrived in Damascus on Monday for talks ahead of a planned trilateral summit on war-torn Syria.
The top diplomat was welcomed by Syrian Deputy Foreign Minister Faisal Mekdad upon arrival at the airport.
The visit comes amid preparations by Syrian regime forces and allies to attack the northwestern Idlib province, the last major opposition stronghold in Syria.
"Al-Nusra and Hayat Tahrir al-Sham terrorist group must be cleaned out of Idlib," Zarif said in statements.
According to Iran's official IRNA news agency, Zarif will hold talks with Syrian President Bashar al-Assad and Foreign Minister Walid al-Muallem later in the day.
Located near the Turkish border, Idlib has been designated as a de-escalation zone where acts of aggression are expressly forbidden as part of the ongoing Astana process.
Nevertheless, for the past two months, the Idlib de-escalation zone has been the target of particular fierce airstrikes by Russia and Assad regime forces.
A tripartite summit is scheduled to be in Iranian capital on September 7 to discuss the situation of resolving the 7-year conflict in Syria.
The summit, which will be held at the level of heads of state and foreign ministers, will be held as a follow-up to the Astana meeting held in Kazakhstan in mid-March.
Iran and Shia group Hezbollah are strong allies of the Bashar al-Assad regime, whose forces have been fighting opposition groups in a deadly civil war since 2011.
Since then, hundreds of thousands of people are believed to have been killed and millions more displaced by the conflict.
