BERLIN (AFP) - Germany's aviation regulator said Sunday it had no previous knowledge of Germanwings co-pilot Andreas Lubitz's struggle with severe depression before the disaster in the French Alps.

A spokeswoman for the Federal Aviation Office (LBA) told AFP that parent company Lufthansa had given it "no information about the medical background" of Lubitz, who prosecutors allege deliberately crashed the plane last month, killing all 150 people on board.

In particular, Lufthansa physicians who examined Lubitz did not make the authorities aware of an "earlier phase of serious depression", said the LBA, which issues pilots' licences.

It said it first learned of Lubitz's mental health problems when it gained access to his file at Lufthansa's Aeromedical Centre on March 27, three days after the crash.

The LBA spokeswoman was confirming a report in the Welt am Sonntag newspaper.

The report said Lubitz had been examined at least six times by Lufthansa doctors since 2009 but after a psychological test was ordered that year, no further mental health evaluations were carried out.

The newspaper quoted Lufthansa as saying that it declined to comment due to the ongoing investigation into the crash of the flight which was bound for the western German city of Dusseldorf from Barcelona.

Lufthansa chief Carsten Spohr has said the airline was unaware of any health issues that could have compromised Lubitz's fitness to fly, calling him "100-percent airworthy".

But the German flag carrier acknowledged last week that Lubitz had informed its flight school in mid-2009, when resuming training after a lengthy medical absence, that he had suffered from "previous episode of severe depression".

He later received the medical certificate confirming he was fit to fly.

German prosecutors said last week that Lubitz was diagnosed as suicidal "several years ago", before he became a pilot, but doctors had recently found no sign he intended to hurt himself or others.

However Lubitz was receiving treatment from neurologists and psychiatrists who had signed him off sick from work a number of times, including the day of the crash.

Ripped up sick notes were found in a flat used by Lubitz, which authorities believe indicates that the 27-year-old was trying to hide his illness from his employer.

A European Aviation Safety Agency spokeswoman told AFP Saturday that it had voiced concerns over Germany's "non-conformity" with air safety rules before the crash, especially on air crew health monitoring.