A German military helicopter crash in Mali last year was caused by Airbus technicians failing to properly install the plane's rotors after a repair operation, a German defense official said on Wednesday.

The official said an investigation into the accident that killed the two pilots found that the crash did not result in a technical failure.

The helicopter was on a mission to support a peacekeeping mission in the Mali desert when it was heavily hit, causing the rotors to crash during the fall.

The report found that Airbus technicians failed to properly install the rotors after a repair operation at a base in Fritzler, central Germany.

Airbus said today that an investigation by Germany found that improperly installed rotary controls were "one of the factors in a series of events" that led to the collapse of the Tiger helicopter in Mali last year.

The company said precautionary measures had been taken to prevent it from recurring. The investigation has ruled out any problems with the design of the plane, it said.