EU regulators have given Volkswagen 10 days to clarify its own admission that nearly a million of the company's cars emit more CO2 pollution than originally claimed, the European Commission said on Tuesday.
In a letter sent to the company on Monday, European Energy Commissioner Miguel Arias Canete asks VW CEO Matthias Mueller to clearly specify which cars were affected by the "irregularities".
The letter is the first step in a long process that could eventually bring millions of euros (dollars) in fines for VW, which is already embroiled in a huge pollution scandal over diesel emissions.
"I can confirm that a letter from Canete was sent to the CEO of Volkswagen yesterday," Commission spokeswoman Anna-Kaisa Itkonen told a news briefing.
"The letter asks for some clarifications from Volkswagen (and) asks which models of cars are affected by the irregularities that Volkswagen reported November 3 as well as how many vehicles affected," she said.
The EU, which has been criticised for its silence during the VW diesel scandal, has significantly more power when it comes to carbon emissions, the pollution behind the greenhouse effect and climate change.
In an email to AFP, Volkswagen confirmed the letter and said its staff would decide on its response "after an internal deliberation".
In the letter, which was first revealed by the Wall Street Journal, the EU requests a response within 10 days.
VW is deeply engulfed in a scandal that was initially centred on so-called defeat devices -- sophisticated software fitted into diesel engines to skew the results of tests for nitrogen oxide emissions.
- Shock admission -
But in a shock admission last week the company said it had underreported carbon emissions to EU regulators on around 800,000 cars in Europe.
In a further setback, Fitch ratings agency on Monday slashed Volkswagen's credit rating, saying that the cheating scandal has exposed worrying corporate dysfunctions at the German auto giant.
Volkswagen is facing potentially tens of billions of dollars' worth of fines, compensation costs and lawsuit damages in the case, which has deeply shaken the world's number-two automaker.
Belgium has opened an enquiry into the Volkswagen emissions scandal, the Brussels prosecutor announced Tuesday.
The Brussels public prosecutor has launched an inquiry "including for false written information in the civil and commercial fields," the prosecutor's office said in a statement.
Similar action is also under way in Germany, France, Italy and Spain.
On Monday Volkswagen's US arm offered owners of its diesel cars, tainted by an emissions scandal, a "goodwill package" of $1,000 worth of gift and fidelity cards on Monday.
Volkswagen, based in Wolfsburg, Germany, on Monday started the difficult task of convincing unions to accept cutbacks it says are necessary to survive the crisis.