US environmental regulators have asked Mercedes-Benz for emissions data after a private lawsuit accused the German carmaker of installing emissions-cheating technology on diesel models, a government spokeswoman said Monday.

The request from the Environmental Protection Agency (EPA) follows up on a civil class-action lawsuit filed earlier this month that said 14 Mercedes diesel models contain technology that spew excess emissions of nitrogen oxide, while concealing the mechanism from regulators.

The suit from plaintiffs firm Hagens Berman takes aim at Mercedes's BlueTEC diesel technology, which the luxury automaker has touted for its environmental benefits.

"We know about the lawsuit," said EPA spokeswoman Julia Valentine. "We have contacted Mercedes and requested the test results for the US diesel engines."

A Mercedes spokeswoman said the carmaker, owned by Daimler, had received the EPA request and is preparing a response.

"We consider this class-action suit to be unfounded," she said. "We will defend ourselves by all legal means."

"We take the protection of the environment very seriously and appreciate the past trust and cooperation with US regulatory agencies."

The Hagens Berman suit likened the issue at Mercedes to the scandal that has enveloped German rival Volkswagen, which has faced a torrent of criticism and government probes after acknowledging that it installed "defeat devices" to flout emissions rules on some 11 million cars worldwide.