Barcelona star Neymar was called to give evidence this week in a murky case over the deal which brought the Brazilian to the Catalan giants from Santos in 2013 (AFP Photo/Curto De La Torre)

Sao Paulo (AFP) - Barcelona and Brazil's star striker Neymar suffered a fresh legal blow Tuesday when Brazilian prosecutors filed a tax fraud and forgery case against him.

The 23-year-old and his family have denied any wrongdoing over alleged irregularities in his superstar signing for Barcelona in 2013.

But hours after he gave testimony in Spain in one case, a new front opened up as federal prosecutors in Brazil launched proceedings against him and his father.

Investigators in both countries suspect Neymar's family and the club hid the real value of the deal under which Barcelona signed him from Brazilian side Santos.

Barcelona valued the transfer at about 57 million euros ($62 million), but Spanish authorities think it added up to more than 83 million euros.

Brazil's federal prosecution service accused the player, full name Neymar da Silva Santos Junior, and his father of forging contracts to pay less tax.

It made the same accusations against his father and two senior FC Barcelona management figures: the club's current president Josep Maria Bartomeu and his predecessor Sandro Rosell.

A federal court must now decide whether to admit the charges and put them on trial.

Last September, Brazilian authorities froze $47 million worth of the player's assets pending investigations.

The federal prosecution service said in a statement the charges related to "tax evasion and forgery," which cost the state "millions" in lost taxes.

- Selfies at court -

Wearing jeans and sunglasses, Neymar seemed relaxed as he arrived at Spain's National Court in Madrid with his father Neymar da Silva Santos, who was also called to testify before an investigating judge.

The player signed an autograph in front of a group of photographers before giving the thumbs-up and entering court, where he stayed an hour and a half.

He made no comment when he left, but took a multitude of selfies with young supporters.

Neymar and his father have defended themselves in the media.

"Before saying nonsense -- that we hid this, or hid that -- they should prove it," Neymar told Brazilian TV station Globo on Sunday.

"My father is doing everything to ensure that I can just focus on playing football. He handles the books. But in the moment when you see someone you love suffering, it starts to hurt."

Bartomeu and Rosell refused to testify when called this week, insisting on the account they had given for a previous hearing.

- Barca's legal battles -

A representative of Santos told the judge on Monday the club had felt cheated by Neymar and his father after details of the transfer emerged.

Fatima Cristina Bonassa said during a five-hour testimony that the footballer was an adult at the time of transfer and knew what he was signing.

The transfer helped Barcelona form one of the world's most lethal football strike forces, along with Argentine superstar Lionel Messi and Uruguay's Luis Suarez.

But the club has faced numerous legal headaches off the field. Messi himself has been called to stand trial from May 31 for tax fraud in a separate case.

Neymar's case hasn't affected his performances on the field. He helped Barca to a treble title triumph last season.

Brazil's golden boy is now expected to captain his country on home soil at the Rio Olympics in August.

"Neymar is perfect," said Barcelona coach Luis Enrique, commenting on the scandal.

"From zero to one million, it affects him at 0.000001 percent," Enrique said.

"It has nothing to do with football, this is an issue that will be resolved as it should be."