Iran's official IRNA news agency is reporting that head of the country's railways has resigned over the deadly collision of two trains in the north of the country which killed 45 passengers.

The Sunday report says Mohsen Pour Seyyed Aghaie summited his letter of resignation on Sunday and it was accepted by Minister of Transportation Abbas Akhoundi.

IRNA quotes Aghaie as saying the accident was caused by "wrong decisions."

On Saturday, Iranian authorities detained three employees of the state railroad company over the incident.

The accident happened on Friday when a moving passenger train slammed into a second train that was parked at a station. Some of the victims were so badly burned that the bodies had to be identified through DNA testing.