"Brigadier General Shahrokh Daipour ... was martyred in the town of Albu Kamal in Syria during a mission to advise Syrian pro-government forces," according to the Guards' Sepah News.

The brief report did not give the circumstances of the officer's death.

He was described as a former unit commander who was wounded during the 1980-1988 Iran-Iraq war before holding various positions involved with artillery.

Iran, along with Russia, is a key supporter of Syrian President Bashar al-Assad.

Tehran denies sending professional troops to fight in Iraq and Syria, saying it has only provided military advisors and organised brigades made up of volunteers from Iran, Afghanistan and Pakistan.

Albu Kamal, in Deir Ezzor province, was the last major town in Syria held by the Islamic State group until its fall in November.

Its recapture by pro-government forces was the final nail in the coffin of the jihadists' self-styled "caliphate" declared across swathes of Syria and Iraq in 2014.

But a major assault by IS on Albu Kamal earlier this month that left dozens of pro-regime fighters dead underscored the continued threat posed by the jihadists.