Airports across Germany were hit by an information system outage that affected police border control systems, leading to disruptions and longer queues to enter the country for passengers arriving from outside the European Union's Schengen area.

"At the moment we have an IT system outage across the country," a federal police spokesman confirmed, asking police officers to manually process passports from outside the Schengen area.

The cause of the failure is still unknown. It led to queues of people at border controls at several German airports, including Frankfurt, the country's busiest.

Berlin Airport also confirmed longer immigration waiting times for non-Schengen passengers.

Regional public broadcaster WDR reported that passengers waited two hours to enter the country, while others were detained on the plane.