TEMPO.CO, Frankfurt - The scandal engulfing Volkswagen, which has admitted cheating diesel vehicle emissions tests in the United States, spread on Tuesday as French minister called for an EU-wide probe.

"It has to be done at a European level," French Finance Minister Michel Sapin said on Tuesday told Europe 1 radio. "We are a European market with European rules. It is these that have to be respected. It is these that have been violated in the United States."

The German carmaker's shares fell to a new three-year low in early trade, extending Monday's 19 percent plunge after it admitted to using software that deceived U.S. regulators measuring toxic emissions.

At 0845 GMT, Volkswagen shares were down 6.3 percent at 123.85 after touching a low of 123.4 euros. The European auto sector index was down 4 percent, as analysts speculated all carmakers could face more stringent tests from regulators.

Europe's biggest automaker could face penalties of up to $18 billion in the United States, as well as class-action lawsuits from buyers and damage to its reputation, with U.S. regulators alleging it misled them for more than a year.

VW, which for several years has been airing U.S. TV commercials lauding its "clean diesel" cars, was challenged by authorities as far back as 2014 over tests showing emissions exceeded California state and U.S. federal limits.

VW attributed the excess emissions to "various technical issues" and "unexpected" real-world conditions. It wasn't until the Environmental Protection Agency and the California Air Resources Board threatened to withhold certification for the automaker's 2016 diesel models that VW in early September revised its explanation.

The U.S. Environmental Protection Agency (EPA) said on Monday it would widen its investigation to other automakers. Media reports say the U.S. Department of Justice has also started a criminal probe into the allegations against Volkswagen, which cover VW and Audi-branded diesel models including the Audi A3, VW Jetta, Beetle, Golf and Passat.

The Swiss Federal Roads Office said it was also investigating whether the same type of Volkswagen diesel cars that were sold in the United States were also sold in Switzerland, adding results were due in days.

REUTERS