The Justice Department announced late Thursday that it had charged Giovanni Pamio with conspiracy to defraud the United States, wire fraud, and violation of the US Clean Air Act.

It was unclear whether Pamio was in custody. He is the eighth VW associate charged by the US, according to the German news agency DPA.

Volkswagen admitted in 2015 to installing so-called "defeat devices" in 11 million vehicles worldwide, designed to lower harmful emissions during regulatory tests but not in real on-road driving situations.

Warnings from insiders?

In its press release late Thursday, the Justice Department said an unidentified Audi employee, who had worked in Audi's diesel engine development section, was cooperating as witness in the Audi case.

The department in its complaint said over seven years Audi engineers had warned that pollution control systems used on the concern's engines violated US clean air rules.

In October 2013, Pamio allegedly ordered his subordinates to prepare a presentation describing technology to scrub pollutants from exhaust gases.

Volkswagen has already agreed with US authorities to spend as much as $25 billion (22-billion euros) in the United States to resolve claims.

Compensation in Europe?

Despite VW's admission of wrongdoing in the United States, it says it has not broken the law in Europe and sees no need to compensate European consumers. The carmaker has committed to fixing all affected vehicles by late 2017.

Consumer agencies across Europe have been pushing for compensation for Volkswagen (VW) drivers who bought diesel cars on the strength of their green credentials.

In May, the 28-member EU overcame initial objections from Germany and agreed the outlines of a reform of the emissions checking system for approving vehicles in Europe.

The outcome depends on negotiations between the EU's executive commission, the European Parliament and the influential auto industry.

ipj/bw (Reuters, AP, AFP, dpa)