(CNN) Hundreds of climate activists breached a runway Saturday at Amsterdam's Schiphol airport to try to stop private jets from taking off, in the latest demonstration by protesters aimed at drawing attention to the climate crisis.
Greenpeace Netherlands said "more than 500" Greenpeace and Extinction Rebellion activists were at the airport, one of Europe's largest, on Saturday afternoon, in a press release. A spokesperson for the Schiphol security forces could not confirm that figure.
There were about "more than 300" activists, the spokesperson of The Royal Netherlands Marechaussee, the military force guarding the airport, told CNN.
Robert Kapel, acknowledged it was a "big scale" demonstration but said air traffic was unaffected as the runway was exclusively used for private jets and no flights are scheduled until late Saturday night.
"This morning activists gathered in the forest nearby, carrying flags and banners with slogans such as 'SOS for the climate' and 'Fly no more.' At the same time another group reached the airport from the opposite direction with bicycles," Greenpeace said.
Images from Greenpeace show groups of dozens of demonstrators sitting down on the tarmac by multiple planes on the runway. Further images show demonstrations inside the terminal.
More than 100 arrests "and counting" have been made so far, Kapel said. He added that he thinks all arrests will have been made by 10 p.m. (local time), which is when he said the first flight is scheduled to take off. Security forces have blocked off the area and made it inaccessible from other parts of the airport, he commented.
Protesters "plan to keep air traffic from the private jet terminal grounded for as long as possible," Dewi Zloch, spokesperson of Greenpeace Netherlands, said in a statement.
She continued: "The airport should be reducing its flight movements, but instead it's building a brand-new terminal. The wealthy elite is using more private jets than ever, which is the most polluting way to fly. This is typical of the aviation industry, which doesn't seem to see that it is putting people at risk by aggravating the climate crisis. This has to stop. We want fewer flights, more trains, and a ban on unnecessary short-haul flights and private jets."
Greenpeace warned authorities there would be some kind of action at Schiphol weeks in advance, Zloch, who was on the scene, told CNN. They did not disclose the exact location, she added.
Schiphol Airport CEO Ruud Sondag said activists should "feel welcome, but let's keep things civil."
He was responding to a previous letter from Greenpeace and stated his objective was to achieve "emissions-free airports by 2030 and net climate-neutral aviation by 2050".
"However, this is only possible if we all work together", Sondag said in a statement published Friday.
"Coming together for our environment, the government, and for society, clear laws, regulations, and proper permits are a necessity. We need clarity on that soon," he added.
Elsewhere in Europe, two climate activists were arrested in Madrid in Spain after they each glued one of their hands to the frames of two Goya paintings in the Prado Museum on Saturday.
There was no apparent damage to the paintings, but the suspects are being charged with public disorder and damages, the Spanish National Police press office for Madrid told CNN.
The suspects, two Spanish women, wrote "+1,5C" on the wall between the artworks, which were Goya's masterpieces "Las Majas," according to the police.
Futuro Vegetal, a Spanish activist group, tweeted a video on the museum protest. The group is taking responsibility for the incident.
They described themselves as a "collective of civil disobedience and direct action in the fight against the Climate Crisis through the adoption of a food growing system based on plants."
"Last week the UN recognized the impossibility of keeping ourselves below the limit of the increase, of the Paris Accord, of 1.5 degrees (C) temperature, with respect to pre-industrial levels," Futuro Vegetal wrote in its tweet.
Security guards at the Prado quickly alerted the National Police, which has a unit dedicated to protecting the perimeter of the famed museum, and officers made the arrests in just minutes, the Police press office said.
The Paris Agreement, which was adopted by 196 parties at the United Nations' COP 21 in December 2015, aimed to limit global warming to 1.5 degrees Celsius.
The protest comes just a day before the COP27 climate conference is due to start in Egypt.