BERLIN (AP) -- Volkswagen CEO Martin Winterkorn stepped down Wednesday, days after admitting that the world's top-selling carmaker had rigged diesel emissions to pass U.S. tests during his tenure.
In a statement, Winterkorn took responsibility for the "irregularities" found in diesel engines but said he was "not aware of any wrongdoing on my part."
"Volkswagen needs a fresh start -- also in terms of personnel," he said. "I am clearing the way for this fresh start with my resignation."
See Winterkorn throughout his tenure as CEO:
Martin Winterkorn, former Volkswagen CEO
Volkswagen CEO steps down, takes responsibility for scandal
WOLFSBURG, GERMANY - MARCH 13, 2014: In this file photo Volkswagen CEO Martin Winterkorn attends the company's annual press conference on March 13, 2014 in Wolfsburg, Germany. Winterkorn announced on September 22, 2015 that he will not step down following the diesel emissions scandal that Volkswagen has admitted could affect up to 11 million VW cars. (Photo by Sean Gallup/Getty Images)
WOLFSBURG, GERMANY - SEPTEMBER 23: Rain clouds are seen over a Volkswagen symbol at the main entrance gate at Volkswagen production plant on September 23, 2015 in Wolfsburg, Germany. Volkswagen CEO Martin Winterkorn and other members of the supervisory board are believed to be meeting inside the headquarters to discuss the Volkswagen Diesel emission scandal, which affects 11 million vehicles worldwide. (Photo by Alexander Koerner/Getty Images)
SONNEFELD, GERMANY - SEPTEMBER 23: The dual exhaust pipes on a Volkswagen turbodiesel passenger car are visible below the vehicle on September 23, 2015 in Sonnefeld, Germany. The inner circle of the Volkswagen governing board is meeting today to discuss the current diesel emissions scandal that has already caused the company's stock market value to plummet approximately 30% since Monday. Volkswagen CEO Martin Winterkorn has admitted the company installed software into 11 million of its diesel-powered passenger cars that manipulates emissions results under testing circumstances. The U.S. Environmental Protection Agency (EPA) first announced the discovery of the software and is planning to fine Volkswagen up to USD 18 billion.(Photo by Sean Gallup/Getty Images)
CEO of Volkswagen AG Martin Winterkorn (R) and CEO of Porsche AG Matthias Mueller (C) are seen speaking with German Chancellor Angela Merkel (L) at the 66th IAA auto show in Frankfurt am Main, western Germany, on September 17, 2015. Angela Merkel called for 'full transparency' from VW in the company's cheating scandal. German auto giant Volkswagen revealed on September 22, 2015 that 11 million diesel cars worldwide are equipped with devices that can cheat pollution tests, a dramatic expansion of a scandal that immediately sent its shares plummeting by another 20 percent. AFP PHOTO / ODD ANDERSEN (Photo credit should read ODD ANDERSEN/AFP/Getty Images)
BERLIN, GERMANY - MAY 30: Chairman of the board of directors of Volkswagen Martin Winterkorn lifts the trophy next to Klaus Mohrs (R), mayor of the city Wolfsburg, during the VfL Wolfsburg Champions party after winning the German DFB Cup Final at Spindler & Klatt on May 30, 2015 in Berlin, Germany. (Photo by Martin Rose/Bongarts/Getty Images)
CEO of German car maker Volkswagen (VW), Martin Winterkorn, attends the shareholders' annual general meeting of VW AG in Hanover, central Germany, on May 5, 2015. German auto giant Volkswagen held its first ordinary shareholders' annual general meeting since a bitter power struggle at the top of the company led to the resignation of VW patriarch Ferdinand Piech as supervisory board head. AFP PHOTO / JOHN MACDOUGALL (Photo credit should read JOHN MACDOUGALL/AFP/Getty Images)
Martin Winterkorn, chief executive officer of Volkswagen AG (VW), pauses during the re-opening of a VW showroom in Berlin, Germany, on Tuesday, April 28, 2015. Volkswagen said 11 million vehicles were equipped with diesel engines at the center of a widening scandal over faked pollution controls that will cost the company at least 6.5 billion euros ($7.3 billion). Photographer: Krisztian Bocsi/Bloomberg via Getty Images
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Winterkorn's statement followed a crisis meeting of the Volkswagen supervisory board's executive committee. Its acting chairman, Berthold Huber, told reporters moments later that company directors are "resolved to embark with determination on a credible new beginning."
There was no immediate decision on a new CEO. Huber said that will be discussed only at a board meeting on Friday.
Winterkorn said VW must continue providing "clarification and transparency."
"This is the only way to win back trust. I am convinced that the Volkswagen Group and its team will overcome this grave crisis," he added.
VW shares were up 8.7 percent at 121 euros following his resignation.
The share price still has a long way to go to recoup the nearly 25 billion euros (around $28 billion) wiped off its market value in the first two days of trading after the U.S. Environmental Protection Agency announced that VW is violating the Clean Air Act.
Winterkorn, VW's boss since 2007, had come under intense pressure since the disclosure that stealth software makes VW's 2009-2015 model cars powered by 2.0-liter diesel engines run cleaner during emissions tests than in actual driving.
The EPA accused VW of installing the "defeat device" in 482,000 cars sold in the U.S. VW then acknowledged that similar software exists in 11 million diesel cars worldwide.
Huber said that "Mr. Winterkorn had no knowledge of the manipulation of emission values" and praised the departing CEO's "readiness to take responsibility in this difficult situation for Volkswagen."
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Before the scandal broke, Winterkorn, 68, had been expecting to get a two-year contract extension, through 2018, at Friday's board meeting.
His resignation came only a day after he issued a video message asking staff and the public "for your trust on our way forward."
The EPA said Volkswagen AG could face fines of as much as $18 billion. Other governments from Europe to South Korea have begun their own investigations, and law firms have already filed class-action suits on behalf of customers.
VW directors renewed pledges of a thorough investigation after Winterkorn's resignation.
"We will clear up these events with all the possibilities we have inside the company and ensure that those involved are punished severely," said Stephan Weil, the governor of Lower Saxony state, which holds a 20 percent stake in Volkswagen.
Weil added that the company itself would file a criminal complaint, "because we have the impression that criminally relevant actions may have played a role here."
The prosecutors' office in Braunschweig, near VW's Wolfsburg headquarters, said earlier Wednesday that they are collecting information and considering opening an investigation against employees of VW who might be responsible.
Prosecutors said they already received "several" criminal complaints. Anyone can file a criminal complaint in Germany, and prosecutors must decide whether to act on them.