In a statement on Monday, Hezbollah condoled Syrian President Bashar al-Assad and the Syrian nation over the death of the senior diplomat.
The resistance group paid tribute to Muallem, saying he always stood by the Palestinian nation, Lebanon and the resistance front, al-Manar reported.
Syria lost a great man who always defended the country’s unity and sovereignty and also served the Arab and Muslim world issues, the statement added.
Muallem passed away at the age of 79 on Monday. The cause of his death was not immediately revealed, but back in 2014 he reportedly underwent heart surgery at a Beirut hospital.
Muallem served as Syria’s top diplomat since 2006 while also serving as the country's deputy prime minister since 2012, over almost the entire nearly decade-long foreign-backed militancy in Syria. Back in the 1990s, he was Syria's ambassador to the US.