Daimler (DAIGn.DE) on Sunday said the United States Environmental Protection Agency had requested information from its luxury car brand Mercedes-Benz to explain emissions levels in some of its cars.

A spokesman for Daimler said they are fully cooperating with the request for information, and that Mercedes-Benz cars conform with all rules and norms.

The EPA declined to comment.

Daimler said the EPA request for information comes in response to a class-action lawsuit filed by law firm Hagens Berman on Feb. 18, 2016, in the U.S. District Court for the District of New Jersey.

The suit accuses Mercedes of deceiving consumers with false representations of its BlueTEC vehicles, which it marketed as "the world's cleanest and most advanced diesel."

A Daimler spokesman said the suit is wholly unfounded and without merit.

The lawsuit alleges the automaker knowingly programmed its Clean Diesel vehicles to emit illegal, dangerous levels of nitrogen oxide (NOx) at levels 65 times higher than those permitted by the EPA when operating in temperatures below 50 degrees Fahrenheit.

Daimler said its cars conform to all relevant rules and regulations.

Daimler however said that under certain circumstances, a system to treat exhaust fumes can operate at a level of reduced effectiveness to prevent condensation from building up in the exhaust system. The condensation could otherwise lead to corrosion and damage the overall effectiveness of the engine and exhaust system.

This is permissible and not illegal, a spokesman said late on Sunday.

German daily Handelsblatt was first to report the EPA request for information. In its Monday edition, Handelsblatt quotes EPA director Christopher Grundler, as saying, "We know about the lawsuit. We have contacted Mercedes and requested the test results for the U.S. diesel engines."