The chief executive of German airline Lufthansa says unannounced tests to check pilots for prescription drugs might help improve air safety.

Carsten Spohr made the comments in an interview with the Frankfurter Allgemeine Zeitung, two months after a plane belonging to Lufthansa subsidiary Germanwings crashed in the French Alps.

Prosecutors believe co-pilot Andreas Lubitz deliberately steered the plane into a mountain, killing all 149 people on board, after hiding psychological problems from his employer.

Lufthansa will propose the spot checks to a task force set up by Germany’s airline industry in the wake of the crash.