More than 300 people are dead following the crash of a military plane in Iran's southeastern mountains.

Rescuers who reached the site said there were no survivors.

The plane, a Russian-made Antonov airliner operated by the Turkish military, was carrying 302 people, most of them members of the elite Iranian Revolutionary Guards.

Blackened spot indicates crash site  (AP PHOTO)
Blackened spot indicates crash site (AP PHOTO)

It is the worst-ever plane crash in Iran. Previously, the worst air disaster was the shooting down of an Iranian airliner by the USS Vincennes in 1988. All 290 people onboard that unarmed, civilian A-300 Airbus were killed.

Wednesday's crash of the Antonov happened about 800 kilometres southeast of Tehran. The plane went down in a mountainous region about 30 kilometres from its destination.

The official Islamic Republic News Agency said all of the people onboard the plane - both passengers and crew - were members of the Revolutionary Guards.

The Guards are under the direct control of the country's supreme leader, Ayatollah Ali Khameni. They are seen as defenders of the Islamic regime and are responsible for protecting borders and defending ruling hardliners.