Berlin Brandenburg Airport on Thursday said it closed its take-off and landing runways after several people gained access to an area closed off to the public.
A climate group known as the Last Generation said its activists glued themselves to the tarmac.
The activists called on the public to stop travelling by air and on the government to stop subsidising it, the group said on Thursday.
“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,” Berlin police said on Twitter.
An airport representative said police had detained the activists but the runways were closed in order for staff to check for and rule out the presence of others.
The representative could not say how many flights were affected.