Killer pilot Andreas Lubitz was declared 'fit to fly' by Lufthansa doctors even though they knew he was being treated for depression, it was claimed today.

Citing documents found by Germany’s air transport authority, the Bild newspaper in Germany claimed that Lufthansa doctors wrote “Lubitz should continue to receive psychological treatment, even though he was deemed fit to fly” by an independent expert in 2009.

Prosecutors in Dusseldorf are now considering corporate manslaughter charges against the airline, it has also been claimed.

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The report does not specify if Lubitz had indeed benefited from continued treatment.

Lubitz had also been classed fit to fly by an independent expert according to reports in Germany

But Germany's air saftey watchdog, the Federal Aviation Authority (LBA), discovered an "explosive note" stating that he continued being treated for psychological problems afterwards.

"This irritated us greatly," an official told the newspaper.

Earlier last week Lufthansa was cleared of wrongdoing in allowing Lubitz, 27, to fly even though he was depressed. Lufthansa officials said he hid his condition from them.

On March 24 he steered a Germanwings Airbus into a French mountainside, killing himself and 149 innocent passengers and crew members.

Black box flight recorders show he locked Captain Patrick Sondenheimer out of the cockpit when he went to use the bathroom.

Ever since details have poured out about his fragile state of mind, particularly about what his Lufthansa bosses knew of his condition.

Tragic: All 150 passengers and crew were killed in the French Alps crash (
Image:
Reuters)

The revelations surrounding what Lufthansa knew about Lubitz' mental health problems is likely to further anger grieving relatives.

A spokesman said:"We cannot answer these questions in order not to prejudice the investigation of the prosecutor."