Barcelona footballer Lionel Messi in court with his father over allegations he owed €4million in taxes

Relaxed: Barcelona forward Lionel Messi was smiling as he arrived at court in Gava to face tax fraud charges

Star attraction: Plenty of supporters turned up to see Messi arrive at court to face tax fraud charges

Charged: Messi's father Jorge arrives at court in Gava to face charges of tax evasion

If the case goes to trial and Messi and his father are found guilty, they could face a fine reaching 150 percent of the amount of back taxes and possible prison time.

In the complaint, state prosecutor Raquel Amado alleges that from 2006-09 Messi 'obtained significant revenue derived from the transfer to third parties of his image rights, income which should have been taxed.'

The complaint says Messi 'circumvented his tax obligations' by using shell companies in tax havens such as Belize and Uruguay.

Messi and his father have always denied any wrongdoing. They have received the backing of Barcelona president Sandro Rosell and former president Joan Laporta, who was head of the club during the years covered in the complaint.

Messi, wearing a suit but no tie, arrived looking relaxed and smiling at the courthouse an hour after his father.

Denial: Barcelona and Argentina star Messi has previously insisted he has done nothing wrong

Messi was cheered on by a group of fans, many of them children, and curious passers-by that grew to around 50 people alongside about 100 journalists and photographers.

Upon leaving the courthouse, several fans chanted 'Messi! Messi!' and a few teenagers chased his car as it sped away down a sunny street.

The case has apparently not distracted Messi at work.

Messi is joint-leading scorer of the Spanish league with seven goals. Barcelona plays at Almeria on Saturday looking to maintain its lead of the league.

The 26-year-old Messi is widely considered the best player of his generation after winning several titles with Barcelona and the highest individual award, the world player of the year, a record four years in a row.

Messi is rated by Forbes as the world's 10th highest-paid athlete. He reportedly earned $41.3 million to June this year, $20.3 million coming from his club salary and $21 million in endorsements.

The soft-spoken Messi had steered clear of scandal in his highly successful career.

Spain has been trying to crack down on tax evasion as it fights to repair the country's public finances amid a double-dip recession.

Finance Minister Cristobal Montoro warned football players in April they should make sure they are 'comfortable' with their tax affairs.

Last year former Barcelona player Luis Figo paid 2.45 million euros in taxes pertaining to image rights from 1997-99.