Volkswagen CEO Martin Winterkorn resigns

"I am doing this in the interests of the company even though I am not aware of any wrongdoing on my part," Winterkorn said after an emergency meeting with Volkswagen directors.

Winterkorn, 68, was Volkswagen CEO for eight years. The German company, which also owns the Audi and Porsche brands, had just achieved his long-standing goal of overtaking Toyota to become the biggest automaker three years ahead of target.

But his position had looked increasingly precarious since the scandal broke Friday, when U.S. regulators said the company had deliberately programmed some 500,000 diesel-powered vehicles to emit lower levels of harmful gases in official tests than on the roads.

The crisis escalated Tuesday when Volkswagen revealed it had found significant emissions discrepancies in 11 million diesel vehicles worldwide.

Winterkorn, an engineer and former head of Audi, said he was stunned by the scale of the misconduct, and was accepting responsibility to clear the way for a "fresh start" for the company.

"The process of clarification and transparency must continue. This is the only way to win back trust. I am convinced that the Volkswagen Group and its team will overcome this grave crisis."

The company's stock price has crashed, causing big losses for investors such as the Gulf state of Qatar. Trust has been severely shaken in a brand that is at the heart of German manufacturing and exports.

Winterkorn had apologized profusely, twice, and the company has set aside 6.5 billion euros ($7.3 billion) to cover the cost of recalls and other efforts to limit the damage, trashing its profit forecast for the year in the process.