At least 14 people were killed when two passenger trains collided head-on in southern Poland late on Saturday in one of the country's worst train crashes in more than 20 years.

The two trains carrying an estimated 350 passengers were heading in opposite directions on the same track when they crashed at high speed in a rural area near the town of Szczechociny. At least 54 people were injured.

One of the green-and-cream coloured carriages of an intercity train traveling to Warsaw had jack-knifed upwards from the force of the crash. Other cars had derailed and were lying on their sides.

This certainly is the most tragic train catastrophe in our history in many, many years, said Prime Minister Donald Tusk, who arrived at the site of the crash with several other government officials early on Sunday.

At the moment we cannot with full responsibility give the final number of fatalities. We should expect at least 14, but we fear this number could rise to 15, he added.

Tusk said it was too early to speculate about the cause of the collision, but added that human error could not be excluded.

The fate of the two drivers was not immediately known as the authorities were still identifying the dead bodies

More than 350 firefighters rushed to the scene, but had to carry their equipment by hand because the trains collided in the middle of a field crossed only by the train tracks.

With the aid of a sniffer dog, rescue workers continued to search for other victims in the mass of mangled steel, where Tusk said they found at least one additional body, most likely dead.

I felt the blow, an unnamed survivor told public television. I hit the person before me. The lights went out. Everything flew. We flew over the compartment like bags. We could hear screams. We prayed.

The injured were transported to nearby hospitals. Among the passangers were several Ukrainians along with French and Spanish citizens, but none of them were hospitalised.

One of the trains had been going from Warsaw from to the town of Krakow and the other from the Polish capital to the town of Przemysl.

(Additional reporting by Karolina Slowikowska; Writing by Chris Borowski, editing by Myra MacDonald)