It follows a widening investigation into the automaker. The Environmental Protection Agency (EPA) said Friday that VW rigged nearly half a million cars to defeat U.S. smog tests.

The company then admitted it intentionally installed software programmed to switch engines to a cleaner mode during official emissions testing. The software then switches off again, enabling cars to drive more powerfully on the road while emitting as much as 40 times the legal pollution limit.

“In my German words: we have totally screwed up,” the head of Volkswagen's U.S. division, Michael Horn, told an audience in New York on Monday.

In a statement Tuesday, Volkswagen gave more details, admitting that there were “discrepancies” related to vehicles with Type EA 189 engines and involving some 11 million vehicles worldwide. The number of vehicles involved is more than the 10 million or so cars it sold in 2014.

New York Attorney General Eric. T. Schneiderman said he had opened an investigation and would collaborate with other states to enforce consumer and environmental protections in the case.

"No company should be allowed to evade our environmental laws or promise consumers a fake bill of goods," Schneiderman said in a statement announcing the probe.

Lawmakers in Tennessee plan to hold hearings over whether the Volkswagen emissions scandal could imperil the nearly $900 million in state and local incentives that have been directed toward the German automaker's lone U.S. plant in Chattanooga.

Republican state Sen. Bo Watson, who has been a vocal critic of Volkswagen's labor policies, cited the state's "significant investment" into the Chattanooga plant in calling for a Senate Finance Committee hearing.

"I am very concerned as to the financial impact these violations could present to the state of Tennessee," Watson wrote in a letter to the panel's chairman. "Any action that threatens the stability and sustainability of the investment should be reviewed by the finance committee, without delay."

The crisis has sent shockwaves through Germany, with Chancellor Angela Merkel calling for “complete transparency” from a company long seen as a beacon of the country's engineering excellence, and newspapers putting the blame squarely on Winterkorn.

Meanwhile, France has launched a probe into whether the carmaker had also used the suspect software in some of its diesel cars in France, the country's environment minister said on Tuesday.

Environmental Minister Segolene Royal said in a statement that she had asked the EPA for further information about the fraud committed by Volkswagen. She also asked French car firms to ensure that similar practices had not taken place in their companies. South Korea also said it would investigate emission levels of Volkswagen diesel vehicles.

German Transport Minister Alexander Dobrindt said there was no indication so far that other carmakers aside from Volkswagen were involved in the scandal.

“We are talking with the Americans, with the environmental authorities and the automobile sector and we currently have no other information” about the possible involvement of other carmakers, Dobrindt told a news briefing.

On Tuesday, VW said it is setting aside around $7.3 billion to cover the fallout from the scandal, including necessary services measures and what it called “other efforts to win back the trust of our customers.”

That figure, it conceded, may be subject to revaluation in the light of ongoing investigations.

Wire services