Brazilian football great Ronaldinho will remain in pre-trial detention in Paraguay after a judge on Tuesday rejected his lawyer's request that he be released on bail or to house arrest.

The 39-year-old World Cup winner and his brother Roberto were arrested on Friday, accused of being in possession of fake Paraguayan passports. "The judge rejected the defense's request for conditional release or house arrest," said prosecutor Osmar Legal.

Judge Gustavo Amarilla cited the seriousness of the case and the discovery of new evidence, as well as the involvement of public officials and business people who facilitated Ronaldinho's arrival in Paraguay. Those factors meant the former footballer needed to be kept in Asuncion "so that there is no obstruction to the investigation," he said.

Amarilla acknowledged the measures taken against the brothers were harsh but said it was his "responsibility not to hinder an investigation," which could be the case if the suspects "were to flee" the country. Legal said he opposed house arrest because the property offered as a guarantee was only valued at $750,000 to $800,000. "It's a tiny amount given the economic solvency of one of the" accused, he said.

Ronaldinho and his brother are spending a fifth day in a police cell in Asuncion. They arrived in Asuncion from Brazil on Wednesday and showed their passports to immigration police, who did not immediately notice any problem with the documents.

Hours later, when the passports were determined to be fake, investigators raided the football star's hotel room and seized the brothers' identity cards and travel documents.

Fake passports

Ronaldinho said the passports had been given to him by people who had invited him to attend conferences sponsored by charities working with disadvantaged children. A Brazilian businessman has also been arrested in connection with the fake passports, while two Paraguayan women have been placed under house arrest and Paraguay's migration director has resigned.

Ronaldinho's Brazilian lawyer Sergio Queiroz has said the brothers were given the Paraguayan passports "to facilitate the possibility of doing business" in Paraguay. "Ronaldinho did not commit a crime because he did not know that the passport they gave him was faked," he said.

The administrator of the charity that invited Ronaldinho, Dalia Lopez, has admitted requesting the passports but said she didn't know they were forged.

A warrant has been issued for her arrest. Amarilla said the investigation is looking into possible criminal association and money laundering. Ronaldinho, considered one of the greatest footballers of all time, was one of the stars of Brazil's 2002 World Cup win and played for European giants Barcelona, Paris Saint-Germain and AC Milan, among others.