Survivors have told of a "nightmarish 10 seconds" as their train carriage overturned and was engulfed in flames in a crash in northern Greece.

At least 32 people have died and dozens more were injured in the head-on collision between two trains near the city of Larissa on Tuesday night.

Rescuers have been working through the night to find survivors.

"We heard a big bang," said 28-year-old passenger Stergios Minenis, who jumped to safety from the wreckage.

"We were turning over in the carriage until we fell on our sides and until the commotion stopped. Then there was panic. Cables, fire. The fire was immediate. As we were turning over we were being burned. Fire was right and left," Mr Minenis was quoted as saying by Reuters news agency.

"For 10, 15 seconds it was chaos. Tumbling over, fires, cables hanging, broken windows, people screaming, people trapped."

According to one shaken passenger who spoke to Skai television, "the windows suddenly exploded" and "people were screaming and were afraid".

"Fortunately, we were able to open the doors and escape fairly quickly. In other wagons, they did not manage to get out, and one wagon even caught fire."

• Live updates as dozens killed after trains collide

Fellow passenger Angelos Tsiamouras told local media the crash had felt like an earthquake, while another named Lazos told the newspaper Protothema: "I wasn't hurt, but I was stained with blood from other people who were injured near me."

The passenger train had been travelling from Athens to the northern city of Thessaloniki when it crashed head-on with the other freight train, leading to a fire in at least one of the carriages. The cause of the crash is not known.

About 150 firefighters and 40 ambulances were at the scene, Greek emergency services said, with cranes also used to remove debris.

"It was a very powerful collision," the regional governor of the Thessaly region, Kostas Agorastos, told state-run television.

"This is a terrible night... It's hard to describe the scene."

He said the first four carriages of the passenger train were derailed, and the first two carriages caught fire and were "almost completely destroyed".

"They were travelling at great speed and one (driver) didn't know the other was coming," the governor said.

Footage of the collision's aftermath showed thick plumes of smoke rising from derailed carriages.

Conditions for rescue workers were "very difficult" because of "the severity of the collision", fire service spokesman Vassilis Varthakoyiannis told reporters.

"I've never seen anything like this in my entire life. It's tragic. Five hours later, we are finding bodies," an exhausted rescuer emerging from the wreckage told AFP news agency.

"We are living through a tragedy. We are pulling out people alive, injured... there are dead. We are going to be here all night, until we finish, until we find the last person," another volunteer rescue worker told ERT state broadcaster in comments cited by Reuters.