FRANKFURT (Reuters) -- Former Volkswagen CEO Martin Winterkorn was informed that the carmaker had told regulators it was using emissions defeat devices two weeks before the cheating scandal became public, German tabloid Bild am Sonntag reported on Sunday.
It said it was in possession of a letter sent by an unnamed manager directly to then-CEO Winterkorn on Sept. 4 that said: "In the conversation on 03.09.2015 with the regulator CARB (California Air Resources Board), the defeat device was admitted."
Volkswagen's U.S. CEO, Michael Horn, told a U.S. House of Representatives hearing in October the company had told regulators on Sept. 3 it was using defeat devices.
The letter pointing to Winterkorn could lend weight to the cases of shareholders planning to sue Volkswagen for compensation for the plunge in its share price, saying VW should have told the public as soon as it became aware.
The law firm acting for Winterkorn, who resigned on Sept. 23, could not be reached for comment outside normal business hours.
A Volkswagen spokesman said the company declined to comment on an ongoing investigation.
German financial watchdog Bafin is investigating whether Volkswagen breached disclosure rules when it admitted to falsifying U.S. emissions tests in September. It said last month the probe would probably take several more months.
In parallel with investigations by various authorities, Volkswagen has hired law firm Jones Day to carry out an internal probe into identifying who ordered engineers to develop and install software designed to cheat U.S. diesel-emissions tests, and who knew.
The discovery of the cheating, which U.S. authorities announced on Sept. 18, led to the resignation of several top managers and is likely to cost the automaker tens of billions of dollars.
The news wiped 17 percent, or more than 13 billion euros ($14.2 billion), off Volkswagen's market value on the next trading day.
Volkswagen is expected to present the first results of its investigation in April. It has said so far it has no reason to believe that more than a few people were involved in the cheating, and not at the top level.
