reports in local media here in Berlin:
Captain reported, that atc sent him into a holding and after his "fuel report" they cleared him to land "on the military part of the airport" (perhaps the words of the journo).
Passengers were forced to stay within a/c "several hours" (I do not believe this), military or police officials searched the complete a/c. The crew was not allowed to fly a/c out of Ciampino, AirBerlin needed another crew.