Several environmental groups have launched legal action against Dutch airline KLM over advertisements that promoted flying as a sustainable form of travel. The groups claim KLM violated European consumer law by misleading customers with ads and a carbon offset program that “give a false impression over the sustainability of its flights and plans to address its climate harm.”

Netherlands based campaigners Fossielvrij NL, supported by Reclame Fossielvrij and environmental lawyers from ClientEarth, said they think the lawsuit is the first to challenge alleged “greenwashing” by the airline industry.

“KLM’s marketing misleads consumers into believing that its flights won’t worsen the climate emergency. But this is a myth,” Hiske Arts, a campaigner at Fossielvrij NL, said.

The airline did not immediately respond.

The groups notified KLM in May that they planned to file the lawsuit. It focuses on the airline’s “Fly Responsibly” campaign and its statement that KLM was committed to “the targets defined in the Paris Climate Agreement.”

“The lawsuit will argue that these claims are highly misleading, since KLM’s plan for continual increases in flying is at odds with the rapid and deep emissions reductions across all sectors which (a UN panel) says is needed to avoid the worst impacts of climate breakdown,” ClientEarth said.

Governments agreed in Paris in 2015 to jointly cut greenhouse gas emissions enough to keep global warming “well below” 2 degrees Celsius (3.6 degrees Fahrenheit) since pre-industrial times. The accords included a preferred target of limiting the worldwide temperature rise to 1.5 C (2.7 F).

As part of its campaign, KLM said customers could buy carbon offset coverage to fund reforestation projects and the purchase of biofuels. The environmental groups said the product promoted by the airline to reduce the climate impact of airplanes is illusory.

The groups said the aviation sector won’t reach net-zero emissions if it does not limit the overall number of flights.

“While climate experts warn we need to reduce air traffic to keep a just and livable world within reach, KLM and the airline industry are continuing to focus on growth at any cost and lobbying intensively against climate regulation,” ClientEarth lawyer Johnny White said.

In addition to the lawsuit filed with the District Court of Amsterdam, the environmental groups are seeking a ban on all fossil fuel advertising in the European Union.