Volkswagen knew of potential problems with its diesel engines more than a year before an emissions scandal roiled the German automaker, but the company maintained that officials did not violate financial disclosure laws.
VW last week issued a chronology of the emissions scandal in response to lawsuits from shareholders over the impact of the scandal on the company's stock price.
The synopsis, in part, indicated that former CEO Martin Winterkorn — who resigned in the wake of the controversy — received a memo about a diesel emissions investigation in May 2014 as part of his "extensive weekend mail."
The Environmental Protection Agency disclosed the presence of software to manipulate emissions levels about 16 months later.
In addition to subsequent criminal probes and civil lawsuits, shareholders alleged in lawsuits that VW was required to publicly release information that could negatively impact the value of its shares.
The company responded in last week's statement that those claims were "without merit."
"With respect to the diesel matter, stock price relevance occurred only as of 18 September 2015 when the violation of U.S. environmental regulations was announced," the company said. "Until then, there were no indications whatsoever of information with relevance for the stock price."
VW said that it did not know whether Winterkorn read the May 2014 memo. Subsequent internal reports about diesel problems, meanwhile, were "treated as one of many product issues facing the company."
The New York Times and German paper Bild am Sonntag previously reported that top VW executives knew of emissions problems well ahead of the EPA's September announcement, and the Justice Department alleged in a civil lawsuit that VW "impeded and obstructed" investigators.
VW denied those allegations and said in last week's statement that a group of lower-level employees "whose identity is still being determined" modified engine software.
The scandal ultimately affected about 11 million vehicles worldwide. Most will be repaired in the European Union under a German-approved recall plan, but VW and U.S. regulators remain in discussions about more complicated repairs to comply with stricter EPA emissions limits.