German prosecutors say human error was to blame for a train crash that killed 11 people, charging a 39-year-old signalling worker with negligence leading to the accident.

Key points: German prosecutors find 'human error' to blame for the train crash that killed 11 people

German prosecutors find 'human error' to blame for the train crash that killed 11 people A 39-year-old, experienced signalling worker is charged with negligence

A 39-year-old, experienced signalling worker is charged with negligence His lawyers say 'he is not well'

"If he had complied with the rules ... then there would have been no collision between the trains," Wolfgang Giese, the prosecutor who led the investigation into last Tuesday's accident in southern Germany, said.

"There is no evidence of technical problems ... our investigation shows that this was human error with catastrophic consequences," he added.

Two commuter trains travelling at high speed crashed head-on near the spa town of Bad Aibling last Tuesday, in one of Germany's deadliest accidents in years, with one slicing the other apart, ripping a large gash in its side.

Dozens were also injured in the collision.

The signalling worker, who had allowed two trains from opposite directions to travel on a single track, made an emergency call after realising his mistake, said another prosecutor Juergen Branz.

"But that went unanswered," he said.

Mr Branz said police ran a blood test on the worker on the day of the crash and had found that he was neither under the influence of alcohol nor drugs.

The worker —who has several years of experience in the job — admitted the error on Monday, Mr Giese said, adding that he had not been taken into preventive detention as the action was not deliberate.

In consultations with his defence lawyers, he had however been taken to an undisclosed secure location, Mr Branz said as "he is not well".

Emergency services stand next to the crashed train near Bad Aibling in south-west Germany. ( Reuters: Michael Dalder )

German authorities had said in the immediate aftermath of the disaster that the rail system was fitted with an automatic braking system aimed at preventing such crashes.

But German media had reported that a signalling worker had manually deactivated an automatic signalling system to let the first train — which was running late — go past.

That action would have also shut off the braking system.

Investigators said about 150 passengers were on the trains, which would have usually carried more people had it not been winter school holidays in the region.

The accident is Germany's first fatal train crash since April 2012, when three people were killed and 13 injured in a collision between two regional trains in the western city of Offenbach.

AFP