Indonesia's transport ministry says AirAsia had no permit to fly a route on Sundays, the day flight 8501 crashed.
The AirAsia plane that crashed last weekend was flying on an unauthorised schedule, Indonesia's transport ministry says, adding it had now frozen the airline's permission to fly the route.
Flight 8501 crashed into the Java Sea with 162 people on board en route from Indonesia's second city Surabaya to Singapore early on Sunday, at a flight time that had not been cleared by officials, said director general of air transport Djoko Murjatmodjo.
"It violated the route permit given, the schedule given, that's the problem," he said.
"AirAsia's permit for the route has been frozen because it violated the route permit given."
He said the permit would be frozen until investigations were completed.
A statement from transport ministry spokesman J.A. Barata said AirAsia was not permitted to fly the Surabaya-Singapore route on Sundays and had not asked to change its schedule.
AirAsia had a permit to serve the route only on Mondays, Tuesdays, Thursdays and Saturdays, a ministry spokesman said.