A head-on train collision in Vienna Monday morning that left five passengers badly injured and a further 36 with light injuries was likely caused by "human error", the Austrian Federal Railways (OeBB) said.

In a press release the OeBB stated "a human error from the train director in charge" was the likely cause of the accident.

It is suspected a railway switch had a fault caused by bad weather and had to be switched to manual control by the train director in the district of Penzing, where the accident occurred.

According to the latest investigation results it may have been the case that it had been forgotten to switch a signal, as one of the two trains involved in the crash should not have been permitted to leave its station.

According to earlier reports, the accident occurred at 8:45 a.m. (0745 GMT) in the Penzing district, western Vienna, said the Austrian Federal Railways.

Rescue efforts involved dozens of volunteers and two emergency helicopters and the last passengers were able to leave the train at 10:30 a.m. (0930 GMT).

One passenger was reportedly stuck following the crash, and some passengers were suffering from shock.

An Austrian Federal Railways spokeswoman was quoted by the APA news agency as saying that they would "try to clarify the cause of the collision, but for now the focus is on the care of the passengers."

A final report on the cause of the accident is expected from the accident commission involved in the next few days, the OeBB said.