KLM was sued by Dutch environmental pressure groups which alleges its “Fly Responsibly” ad campaign amounts to greenwashing, in one of the first such lawsuits to hit a major airline. 

KLM, the Dutch arm of Air France-KLM, has run ads that give customers “the false impression that its flights won’t worsen the climate emergency,” breaching  European Union rules, the Amsterdam-based lead campaigner Fossielvrij said in a statement. The lawsuit was filed in a court in the Dutch capital Wednesday morning, according to Fossielvrij.

With commercially-viable alternatives like electric and hydrogen-powered jetliners still at least a decade away, carriers rely on measures like carbon offsetting to reduce their environmental impact. But such programs are usually voluntary programs customers have to fork out extra for. The Netherlands’ advertising watchdog in April ruled that KLM’s promotion telling customers they could fly emission-free is misleading.

The ad’s tag line, “Be a hero, fly CO2 zero,” is an absolute claim, the Dutch Advertising Code Committee said in its verdict. As such, the company has the burden of proving that statement to be true and didn’t meet that test, the committee said.

KLM say on its website its customers have the option of donating toward reforestation projects with its own offset project. In exchange, KLM says it buys certified carbon credits for a reforestation project in Panama. These programs are common practice in the aviation industry. A representative for the airline said no one was immediately available to comment on the lawsuit.

European regulators are taking a much tougher stance on suspicions of greenwashing in other industries too. German police last month raided the offices of asset management firm DWS Group as part of a probe into allegations by a former DWS executive that the company inflated its ESG credentials.