Iran's Foreign Minister Ali Akbar Salehi on Wednesday congratulated Syrian President Bashar al-Assad's regime on its victory over rebels in the battle for the strategic town of Qusayr.
Salehi, in a phone call to his Syrian counterpart Walid Muallem, congratulated "the Syrian people and government for cleansing Qusayr of armed groups," the Fars news agency reported.
He welcomed "the closure of the transit route for the sending of illegal weapons" to the rebels.
Syrian rebels earlier conceded they had lost control of Qusayr, a principal transit point for their weapons and fighters from neighbouring Lebanon.
Qusayr is also strategic for the regime because it is located on the road linking Damascus with the coast, its rear base.
Iran is a predominantly Shiite Muslim country, and a close ally of Assad, who belongs to the Alawite offshoot of Shiite Islam.
Salehi expressed hope that the regime's Qusayr victory could help prepare the ground for a peace conference as proposed by the United States and Russia.
Salehi's remarks were earlier echoed by his deputy Hossein Amir Abdollahian, who criticised Western and Arab countries as well as Turkey, without naming them, for backing the rebels.
"Certain parties continue to send arms and support terrorist actions in Syria," Abdollahian said. They "are responsible for massacres and destruction in Syria and should be tried for war crimes."
Iran, Syria's key ally in the Middle East, is accused by Western and Arab governments of supplying weapons and military advisers to the Syrian regime. Iran has repeatedly denied having any troops on the ground.