German prosecutors searched car giant Volkswagen’s offices Tuesday over the long-running “dieselgate” emissions cheating scandal, the company said, adding it was cooperating with authorities.

“The public prosecutor’s office in Braunschweig executed a search warrant… in the context of investigations directed against individual defendants and relating to diesel vehicles,” VW spokesman Nicolai Laude told AFP.

Hans Christian Wolters, a spokesman for the prosecutors, confirmed a search had taken place but declined to provide details, citing the ongoing investigation.

Laude said the probe was related to the EA 288 engine, a successor to the EA 189 model built into many of the 11 million cars VW admitted in 2015 included so-called “defeat device” software.

Designed to fool regulatory checks, the programmes reduced output of harmful nitrogen oxides in laboratory conditions but allowed the engines to spew many times the legal limit on the road.

VW considers investigations into the EA288 to be “unfounded”, Laude said, adding that a probe by German transport authority KBA in 2016 did not provide any evidence of defeat devices built into the newer engine.

Nevertheless, “Volkswagen proactively disclosed the technical facts underlying the allegations to the responsible investigation authorities and registration authorities at an early stage,” he added.

“Dieselgate” has cost VW more than 30 billion euros ($33.2 billion) in fines, compensation and legal costs — most of it in the US — and prompted bosses to launch an unprecedented shift towards electric mobility.

In Germany, car owners and investors are still pursuing the firm for billions in compensation, including in first-of-their-kind mass lawsuits.