Seven-time motorcycling world champion Valentino Rossi is being investigated for alleged tax evasion, a spokesman from Italy's tax agency said.

The spokesman said the agency was examining possible tax evasion on undeclared revenues of 60 million euros ($A96.65 million) from 2000 to 2004.

The investigation is linked to Rossi's decision in 2000 to take up residence in Britain to take advantage of favourable tax conditions.

Rossi, a sporting hero in Italy, won the 125cc world championship in 1997, the 250cc title in 1999 and the 500cc crown in 2001 before bagging four MotoGP titles from 2002-2005.

However, the 28-year-old lost out to American Nicky Hayden in 2006 and is second in the 2007 standings behind Casey Stoner of Australia with seven races left.

His Yamaha team refused to comment while Rossi's personal management were unavailable.

His father, Graziano Rossi, told Gazzetta Dello Sport's website: "I know nothing about this story and I also don't know where Valentino is."

The next race is in the Czech Republic on August 19.

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