Berlin Brandenburg Airport said on Thursday flights were resuming with some delays after it was earlier forced to close its runways as climate protesters broke into the site and some of them glued themselves to the tarmac.
The activists from the Last Generation environmental group called on the public to stop travelling by air and on the government to stop subsidising it.
"In an airport area that is not open to the public, we encountered several people who had previously gained unauthorised access and some glued themselves (to the tarmac)," Berlin police said on Twitter.
The protest, the latest by climate activists in Germany, also urged the government to expand cheap train travel offers.
"One affluent percent of the population is responsible for around half of flight-related greenhouse gas emissions," Last Generation said in a statement, adding that a 70 year-old man was among the activists in the airport.
A spokesperson for the airport said the activists had entered the airport from two points in the north and south, and police had detained them.
The spokesperson could not say how many flights were affected.
Flight tracking website FlightRadar24 showed some aircraft that were originally heading to the airport changed their route.
Some 13 flights had been diverted to airports in the eastern state Saxony by 6 p.m. (1700 GMT), rbb broadcaster reported, citing Mitteldeutsche Flughafen AG, the company that operates the airports in Dresden and Leipzig.
(Reporting by Riham Alkousaa and Swantje Stein, Editing by Victoria Waldersee and Mark Potter)
