Germanwings Co-pilot Andreas Lubitz, who crashed a plane in the Alps killed all 150 people on board, received treatment for suicidal tendencies several years ago

Dusseldorf prosecutors he had undergone psychotherapy "with a note" about such behaviour for several years before becoming a pilot.

"In the following period, and until recently, further doctor's visits took place, resulting in sick notes without any suicidal tendencies or aggression against others being recorded," said spokesman Ralf Herrenbrueck.

Lubitz locked his captain out of the cockpit and ignored his pleas to open the door before crashing the Barcelona-Dusseldorf Airbus last Tuesday.

Prosecutors said there no evidence showing that Lubitz had any physical ailment affecting his sight following reports he had suffered a detached retina.

But his file at German Federal Aviation Office contained a notation that meant he needed "specific regular medical examination", but it did not specify whether it was for a physical or mental condition. He had been given a third-class medical certificate by the US A

In order to obtain such a certificate, a pilot must be cleared of psychological problems including psychosis, bipolar disorder and personality disorders.

The certificate also means that he was not found to be suffering from another mental health condition that "makes the person unable to safely perform the duties" of a pilot.

At the crash site, authorities are poring over DNA evidence that has been painstakingly collected from among the crash debris scattered across the steep mountainside.

Their goal is to try to identify victims for the grieving relatives who have poured into the area by the hundreds.

Workers laid down a road 1.2 miles long yesterday to reach the remote crash site.

France has deployed some 500 gendarmes and emergency workers to secure the site