Former VW Group chairman Martin Winterkorn and current incumbent Matthias Müller have been accused of covering up diesel emissions cheating for more than a decade by attorneys in the USA.
New York Attorney-General Eric Schneiderman said the company had a "culture of deeply-rooted corporate arrogance, combined with a conscious disregard for the rule of law".
Müller’s involvement is said to relate to the time when he worked at Audi. Schneiderman alleges that in 2006 he signed off on an agreement not to equip some 3.0-litre diesel-powered Audis with larger urea tanks to allow to the engines to meet US environmental standards. Winterkorn is said to have also been aware of the potential issue of not doing so.
The suit does not allege that Müller knew about the fitting of cheat devices on other VW Group diesel cars, which was initially discovered in the US and involves 11 million cars worldwide.
However, it does claim that the use of the illegal software was known at senior levels of the company, and lists directors in several divisions that are alleged to have been involved with the introduction of the software.
The lawsuits - filed by New York, Massachusetts and Maryland - also allege that VW's engineering department deleted incriminating data in August 2015. Schneiderman claimed that some of it had since been recovered, and said it would be presented in court.
The lawsuit filings also claim that a senior attorney working for VW told engineers to destroy evidence a month before the dieselgate scandal broke. “At least eight employees — all in engineering departments involved in the creation of the defeat devices — got the unmistakable message: they promptly deleted or removed incriminating data about the devices from the company’s records,” it says.
VW has consistently maintained that the dieselgate cheats were developed by a small group of rogue engineers. A statement issued earlier this year read: “No serious breaches of duty on the part of any serving or former members of the board of management have been established”.
Winterkorn maintained he was “not aware of any wrongdoing on my part” when he stepped down in the wake of the scandal, but he is now under investigation by German prosecutors on suspicion of possible market manipulation.
In response to the latest allegations, a VW statement read: "It is regrettable that some states have decided to sue for environmental claims now, notwithstanding their prior support of this ongoing federal-state collaborative process.”
VW agreed a $15.3bn (£11.6bn) settlement with federal regulators, several states and owners of the affected vehicles last month.