Adidas, tyre maker Michelin and oil firm Total have come under scrutiny after files concerning foundations linked to the three firms, as well as some 30 French individuals, were handed to the Paris prosecutor's office by the French finance ministry in late 2008.

After considering the files, the prosecutor's office said it would open a preliminary investigation into the firms, the first step towards a possible indictment on charges of dodging taxes and concealing the profits behind Liechtenstein's banking secrecy laws.

All three firms denied being the target of a money-laundering probe.

"The Michelin group does not own a Copa foundation, nor does it hold any accounts at the LGT bank in Liechtenstein," a spokesman for the firm told AFP, denying claims in a report by French daily Le Parisien.

A spokeswoman for energy giant TotalFinaElf said in a statement that it "formally denies" owning a foundation called "Elf Trading" in Liechtenstein, while Adidas told Le Parisien it had no knowledge of any such investigation.

"We have no activities in Liechtenstein, with the exception of two service stations," the Total spokeswoman said in the statement.

French uncovered fraud files after German investigation

The files allegedly linking the three businesses to foundations which are suspected of being fronts for money laundering were uncovered after French authorities launched an investigation after a major German tax evasion scandal uncovered allegedly undeclared accounts held by foreign nationals within Liechtenstein's secretive banking sector.

French Budget Minister Eric Woerth confirmed on LCI television that his ministry had transferred three files to prosecutors, but would neither confirm nor deny the names of the groups involved.

France's finance ministry has been investigating 64 family-owned firms in connection with the scandal, of which 16 have since come clean and paid their overdue taxes and penalties, Woerth said.

Authorities estimated last year that French firms evaded up to one billion euros in taxes via Liechtenstein, of which Le Parisien said Elf, Michelin and Adidas accounted for "a large part".

French President Nicolas Sarkozy recently said France would crack down on money laundering in European tax havens, including Liechtenstein, Luxembourg and Andorra.

Transparency International France estimates that corporate tax evasion via tax havens costs the French state some 10 billion euros per year.

Leaders of the Group of 20 meeting in London this week are set to draw up an international blacklist of tax havens, as worldwide pressure grows to clamp down on uncooperative nations and territories.

Bowing to international pressure, Liechtenstein agreed earlier this month to ease its strict banking secrecy rules and cooperate with foreign governments to combat tax fraud.