Police have closed entrances to the airport in the German city of Hamburg amid chaos caused by a security strike.

Security personnel are staging strikes Monday at airports in Hamburg, Hannover and Stuttgart to press their demands for higher wages.

German news agency dpa quoted Hamburg airport spokeswoman Stefanie Harder describing the situation at the airport as "catastrophic."

About a quarter of all flights there have been canceled.

Officials in Hannover and Stuttgart warned of long queues for security at those airports too.