Climate protest mires flights at Germany's Frankfurt airport as police thwart linked action in London

Frankfurt, Germany — Germany's busiest airport canceled more than 100 flights Thursday as environmental activists launched a coordinated effort to disrupt air travel across Europe at the height of the summer holiday season to highlight the threat posed by climate change. Frankfurt Airport said flights were halted for safety reasons after climate activists breached security fences, triggering a response from police, firefighters and airport security officers.

All runways were back in operation by 7:50 a.m. local time, the airport said in a statement on its website. About 140 flights have been cancelled so far, but further disruptions are expected throughout the day, the airport said.

"We sharply condemn these unauthorized demonstrations, and we reserve the right to take legal action against the participants," the airport said. "Their activities pose severe danger to flight operations — possibly putting human life at risk."