At least 17 people have been killed and 50 more have been injured after a passenger train partially derailed in eastern Iran, authorities said.

Four of the seven carriages in the train derailed in the early morning darkness near the desert city of Tabas, roughly 340 miles south-east of the capital, Tehran, state television reported.

The report said the number of casualties could rise, though initial details about the disaster involving a train reportedly carrying some 350 passengers remained unclear.

Rescue teams with ambulances and helicopters have arrived in the remote area, where communication is poor.

Over a dozen people suffered critical injuries, with some transferred to local hospitals, officials said.

Iranian media quoted the governor of Tabas, Ali Akbar Rahimi, as saying the crash killed at least 17 people and that the number of fatalities may rise as rescuers search the train carriages.

Aerial footage of the desert site of the disaster showed train carriages on their side, with some rescuers running at the scene as they tried to care for the injured.

State TV later aired images from a hospital where the injured received treatment. One of those injured told the broadcaster they felt the train suddenly brake and then slow before the derailment.

"Passengers were bouncing in the car like balls in the air," said the injured passenger.

The derailment happened some 30 miles outside of Tabas on the rail line that links the city to the central city of Yazd.

The report said the crash is under investigation. Initial reports suggested the train collided with an excavator near the track.

Iran's worst train disaster came in 2004, when a runaway train loaded with petrol, fertiliser, sulphur and cotton crashed near the historic city of Neyshabur, killing some 320 people, injuring 460 others and damaging five villages.

Another train crash in 2016 killed dozens of people and injured scores more.