Senior executives at Volkswagen AG including its former chief executive covered up evidence that the German automaker cheated on US diesel emissions tests for years, New York state has claimed in a civil lawsuit against the company.
New York was one of three states bringing separate lawsuits in state courts against VW, along with Maryland and Massachusetts.
The suit filed by New York Attorney General Eric Schneiderman in state court in Albany on Tuesday outlined more than a decade of efforts by the world's no 2 automaker to deceive regulators in the United States and Europe, citing internal VW documents.
VW last September admitted using sophisticated secret software in its cars to cheat exhaust emissions tests, with millions of vehicles worldwide affected.
The New York lawsuit, seeking hundreds of millions of dollars in penalties from VW, charges that dozens of company employees at various levels knew that the company's "clean diesel" engines could not meet pollution standards in normal driving without compromises to performance or fuel economy.
Volkswagen spokeswoman Jeannine Ginivan criticised the decision by the states to file suit, noting the company has already agreed to spend billions of dollars to address all environmental harms from the excess emissions.
Former VW CEO Martin Winterkorn and VW's former global head of marketing, Christian Klingler, knew by spring 2014 "of the existence of unlawful defeat devices and did nothing to prevent both Audi and Volkswagen from repeatedly deceiving regulators", the New York lawsuit stated.
VW has admitted that it installed improper software that deactivated pollution controls on more than 11 million diesel vehicles sold worldwide, and last month agreed to pay US$15.3 billion to settle US federal litigation and charges lodged by 44 US states that the company violated consumer fraud laws.
The US Justice Department and Environmental Protection Agency have not yet reached a deal with Volkswagen on fines as part of separate settlement that could lead to an outside monitor overseeing VW's compliance with US laws. VW also faces a Justice Department criminal investigation.