Germany's civil aviation administration was responsible for the grounding of freight operator Air Cargo Germany, but the authority has yet to explain its decision.
The airline suspended operations on 18 April, without clarifying the reason.
But Germany's aviation regulator, LBA, says it suspended the air operator's certificate and the licence of the carrier.
LBA declines to disclose the reasons for the grounding.
Air Cargo Germany says the interruption of its services is "beyond our control" and was not "foreseen in any way".
"Our shareholders are supporting in any way possible and you can be assured that we work around the clock to find sustainable solutions to recommence our services to you," the airline says in a note to its customers.
"[Air Cargo Germany] will continue to provide its excellent service once this unhappy situation is resolved."
It has been operating a fleet of Boeing 747-400 freighters from its base at Frankfurt Hahn. The carrier's shareholders include Russia's Volga-Dnepr.