US prosecutors have expanded their accusations against German parts supplier Bosch in the emissions scandal that has shaken up Volkswagen over the last year.
Prosecutors are now accusing Bosch, which was already a codefendant in the US class action case, of being an active part of the scandal, according to a copy of the complaint filed to a San Francisco court.
"Bosch was in on the secret and knew that Volkswagen was using Bosch's software algorithm as an 'on/off' switch for emission controls when the Class Vehicle was undergoing testing," the complaint document, which dpa has seen, says.
Previously, Bosch was only suspected of having possibly known, rather than being an active part of the secret.
In September 2015, Volkswagen admitted it had installed software in millions of vehicles that manipulated emissions test results. Last month, the German carmaker agreed with US authorities on a 14.7-billion-dollar settlement deal.
Bosch stands accused of having delivered the necessary software for the so-called "defeat device" that manipulated the emissions data. The company wasn't a part of last month's deal in the US.
Bosch declined to comment on the accusations, citing ongoing legal action.
In addition to the charges in the US, prosecutors in Stuttgart, Germany, are also working on the case, investigating unknown Bosch employees for complicity to fraud.