MADRID: Lionel Messi's spotless image as the world's greatest footballer and a humble man has taken a stunning blow with accusations that he cheated on his taxes, the Spanish media said on Thursday.

Newspapers reacted with shock to news that the Barcelona star and Argentina international has been accused of defrauding the Spanish tax authorities of more than four million euros ($5 million, ?3.4 million).

"A symbol under suspicion," blared the front page of the country's biggest sports daily, Marca, saying in an editorial that he had cast doubt on his image as an exemplary sportsman.

"He has not been condemned, just accused, but the tax authority's account of a supposed fraud is hair-raising," the paper said, adding that the revelations were a surprise.

Madrid-based daily El Mundo said the claim "smears his image" and if proven would be "extraordinarily serious" and should be doubly condemned because of the 25-year-old's high income.

The four-time world player of the year and his father Jorge Horacio Messi have fiercely denied wrongdoing.

"We are surprised about this news because we have never committed any infringement," the striker said in an English-language statement released on his Facebook account on Wednesday.

In a written filing lodged with a court in Catalonia, northeastern Spain, where Messi is a resident, a financial crimes prosecutor accused him and his father defrauding the state of more than four million euros in taxes related to income from the use of his image from 2006-2009.

The striker and his father aimed to "deceive" the taxman by ceding Messi's image rights to companies based in tax havens such as Belize and Uruguay, the prosecutor's complaint said.

The court has yet to decide whether to proceed with the case, however.

The Barcelona-based daily Sport cautioned that the player had not been found guilty and should not be tried by the media.

"Messi does not deserve the injustice of parallel trials," the paper's director Joan Vehils said an opinion piece.

"Investigating him is fine but that he be condemned already without being given a chance to defend himself and without a trial is unacceptable."

Messi's achievements on the field have made him one of the most marketable sportsmen in the world.

The Argentine was ranked 10th amongst Forbes' list of sports stars' incomes this month with an annual $21 million from endorsements alone.

But the complaint lodged with the court in Gava, near Barcelona, accused Messi and his father of defrauding the state of 1.06 million euros in 2007, 1.57 million euros in 2008, and 1.53 million euros in 2009.