FRANKFURT: German auto giant Volkswagen said that an independent probe it has commissioned into the global pollution-cheating scam is likely to take “several months.”

VW, which has admitted to fitting sophisticated software in its diesel engines to skew emission testing, has commissioned US legal firm Jones Day to conduct an independent investigation into the affair that has rocked the entire automobile sector.

Key members of the automaker’s supervisory “are of the opinion that the investigations will take several months before they can be completed,” the company said in a statement.

As a result of the time and energy that the investigation is likely to need, the supervisory board’s steering committee had decided to postpone an extraordinary general meeting that was originally going to be held on November 9, the statement continued.

“It is unrealistic, from a point of view of both time and content, that we will be able within only a few weeks to come up with the informed answers that shareholders can justifiably expect,” VW said.

“Furthermore, the steering committee is of the opinion that the employees involved will be needed to clear up the matter and draw up solutions to the problems. Their work should not be made even more difficult by having to prepare a shareholders’ meeting at the same time,” it said.

Sweden meanwhile said it may send a tax bill to Volkswagen for undeclared pollution of its diesel vehicles after it admitted fitting some 11 million with pollution cheating devices.

Cars sold in the Nordic country have a tax assessed depending on the amount of pollution they emit.

“If it is proved that the emissions were higher than they said then it is possible that certain cars were taxed too little,” Finance Minister Magdalena Andersson said on SR public radio.

She said Volkswagen has been asked for information to help calculate how much the Swedish state may have lost in tax revenue.

Volkswagen said recently it had sold 225,000 vehicles in Sweden fitted with devices that switch on pollution controls when they detect the car is undergoing testing and then switch off the controls when the car is on the road, allowing it to spew out harmful levels of emissions.

Volkswagen Sweden’s chief executive, Claes Jerveland, told the TT news agency that the company would look into the matter, noting that so far concerns had been about the motors emitting higher levels of nitrogen oxides rather than carbon dioxide, upon which the Swedish tax is based.

The tax is paid by car buyers, so the Swedish tax authority would may have some legal hurdles to clear before sending any bill to Volkswagen.

The world’s biggest carmaker by sales, Volkswagen has seen its market value plunge by nearly 40 percent since US authorities accused the company of having fit its cars with software to evade pollution controls.