Never one to put a foot wrong on the pitch, Italy's World Cup winning captain Fabio Cannavaro is being investigated on suspicion of illegally sidestepping one million euros ($1.27 million) in tax.

The former centreback, who led Italy to glory in Germany in 2006, on Wednesday had assets worth 900,000 euros seized or frozen by the financial police in connection with an ongoing probe into a luxury boat rental company owned by Cannavaro, 41, and his wife, Daniela Arenoso, 40.

In a statement, prosecutors in Cannavaro's home city of Naples, said they suspected that three vessels supposedly available for rental through the company were in fact for the couple's private use.

As such, the couple should have declared them as taxable assets and not been able to benefit from the various tax breaks for which only trading companies are eligible.

Tax inspectors have estimated that the operation of what was effectively a sham company, FD Service, enabled the couple to avoid more than one million euros in taxes and VAT between 2005 and 2010.

The prosecutors said they had obtained evidence of Cannavaro's direct involvement in the fraud and of other, unspecified, illegal actions in relation to the company.

Also under investigation is Eugenio Tuccillo, described by prosecutors as an individual of limited means to whom Cannavaro sold the business shortly after the opening of the tax probe.

Almost immediately after taking over, Tuccillo put the company into administration in what inspectors suspect was an attempt to hide the fraud.

In a statement, lawyers for the couple stressed that the company had been run by Cannavaro's wife, said the dispute was a long-standing one and described the tax authorities' suggestion of wrongdoing as "highly debatable".

"In any case, the couple, convinced of the fiscal propriety of their position, have instructed their lawyers to provide the judicial authorities with any necessary clarification, while contesting the confiscation measure taken today."

In an illustrious playing career, Cannavaro played for Napoli, Parma, Internazionale, Juventus and Real Madrid before a final stint with Al-Ahli in Dubai, where he is currently assistant coach.

His movie-star looks, 136 caps and rise from the back streets of Naples to the summit of world football have made him a national icon in Italy, a country that prizes defenders like no other.

Famed for being as tough on the pitch as the teak on one of his boats, Cannavaro had, until now, also enjoyed a very positive image as a dignified family man: the antithesis of the stereotypically brash modern footballer.

The latest revelations may not sully that reputation too much, though, as tax-dodging is often referred to as the second national sport in Italy.

By coincidence, Flavio Briatore, the international playboy and former Formula One team boss, was Wednesday in court in Genova on charges that he pretended to hire out his yacht in order to avoid millions of euros of VAT on its initial purchase and to qualify for an exemption on fuel duty.

A government report published last month estimated that tax evasion currently costs Italy 91 billion euros per year, equivalent to six percent of GDP.

News of the allegations against Cannavaro emerged a day after the financial police announced they had broken up a ring of companies they believe used false accounting to defraud the state out of 1.7 billion euros ($2.2 billion).

Prime Minister Matteo Renzi has promised a crackdown on tax dodgers and has vowed to end the country's tradition of regular amnesties for offenders.

Well-known names who have been previously accused or convicted of illegal tax evasion include fashion designers Giorgio Armani, Domenico Dolce and Stefano Gabbana.

Former prime minister Silvio Berlusconi is currently doing community service in a retirement home as his punishment after being convicted of tax fraud.