Forty-four people were killed and 103 injured when one Iranian passenger train collided with another at a station about 150 miles (250 km) east of the capital Tehran, state media reported.

"I was sleeping when the crash happened. I thought it was an air strike ... When I opened my eyes, there was blood everywhere," a hospitalised passenger told state television.

State television footage showed four derailed carriages, two of them on fire and a spokesman for Iran's Red Crescent, Mostafa Mortazavi, told the semi-official Fars news agency that firefighters were trying to control the blaze.

Senior Health Ministry official later announced via Tasnim news agency that rescue operations had been completed and the final death toll was 44. An investigation into the cause of the crash in the northern province of Semnan was continuing.

Semnan provincial governor Mohammad Reza Khabbaz told Iranian television it appeared that a train entering the Haft-Khan station on the outskirts of Shahroud ploughed into another that had broken down there.

"The initial investigation suggests that a mechanical failure, possibly caused by cold weather, forced the express train, operating between the cities of Tabriz and Mashhad, to stop (at Haft-Khan)," Khabbaz said.

Tabriz state governor Rahim Shohratifar told Tasnim that the moving train had 400 passengers. It was not clear how many passengers were on the stationary train. Fars earlier reported that 100 passengers had been rescued.

Semi-official Mehr news agency said four of the dead were railway employees aboard the trains.

Iran's rail network aged badly under economic sanctions imposed over its disputed nuclear programme, making it difficult to modernise rolling stock, and safety standards suffered.

The sanctions were lifted in January after Iran reached a deal with world powers to limit its nuclear activity.