BERLIN — Lufthansa indicated Monday that it was under no obligation to report to Germany’s national aviation authority the fact that Germanwings co-pilot Andreas Lubitz had suffered from depression before qualifying as a pilot several years ago.

Germany’s Welt am Sonntag newspaper quoted the Federal Aviation Office as saying that it wasn’t informed about Lubitz’s previous depression before the March 24 crash of Flight 9525.

Investigators believe that Lubitz, 27, locked his captain out of the cockpit and deliberately flew the Airbus A320 into a French mountainside. All 150 people on board were killed.

Lufthansa has said Lubitz informed its flight school when he returned from a several-month break in pilot training in 2009 that he had experienced an episode of “severe depression.” It has said he subsequently passed all medical tests.

The Federal Aviation Office said a Lufthansa medical center issued a fit-to-fly certificate in 2009 and sent it to the office, a procedure that was “in accordance with the legal requirements,” Welt am Sonntag reported, adding that it didn’t inform the office about the previous depression.

Lufthansa said in a statement Monday that, under a regulation that came into effect in April 2013, there are different rules on informing the aviation office about “certain medical issues.”