The Brazil coach, Luiz Felipe Scolari, is under criminal investigation in Portugal for suspected tax fraud and money laundering, according to US court documents obtained on Wednesday by the Associated Press.

Portuguese tax authorities suspect €7.4m (£6.05m) that was transferred from Portugal to a bank in Miami between 2003 and 2008, when Scolari was coach of Portugal's national team, was local income that the Brazilian did not declare.

A US district judge last week granted Portugal's request for a series of Miami bank accounts to be examined, Florida court documents show. An assistant US attorney was placed in charge of collecting the evidence.

Tax fraud and money laundering together carry a maximum penalty of 17 years in prison in Portugal, and the investigation is an unwelcome distraction for the Brazil coach as his country prepares to host the World Cup.

The 65-year-old denied any wrongdoing after the court documents were first reported on Monday by OffshoreAlert, a Florida-based site specialising in fraud investigations.

"I have correctly filed all my tax returns. In all the countries where I've worked, I've always declared my income," Scolari said in a statement in São Paulo on Tuesday. "If anything is wrong, it's not my fault. I hope justice gets to the bottom of the facts."

Officials at the Portuguese Football Federation, which employed Scolari as national team coach, did not reply to a request for comment.

Fifa had no comment on the investigation. Fifa's code of ethics can be applied to conduct "that damages the integrity and reputation of football and in particular to illegal, immoral and unethical behaviour". Sanctions for breaching the code range from a warning to a ban from any football-related activity.

Portuguese investigators want to know who were the "real beneficiaries" of numerous payments made into the Miami accounts over the six-year period.

The money went to accounts held by the Netherlands-based Flamboyant Sports, London-based Chaterella Investors Limited and Taliston Financial Corp, a British Virgin Islands company, according to prosecutors. Those companies owned, at various times, non-exclusive rights to the use of Scolari's name, image and voice, they say. Transfers were also allegedly made to Miami accounts in the name of Scolari himself and of his son, Leonardo. The investigators suspect Scolari used those companies and bank accounts to hide income from the Portuguese tax authorities.

Portuguese investigators sent an initial request for assistance to the US justice department in Washington in 2012. It was not clear why the request was submitted to a judge only last week. The judge endorsed the request last Thursday.

The Portuguese attorney general's office acknowledged in an email to the AP that the department for criminal investigation and prosecution has opened an inquiry into Scolari, but it provided no further details. In Portugal, investigations are subject to a judicial secrecy law which forbids the release of details of the case.

Scolari led Brazil to World Cup success in 2002. He has also coached in Japan and the Middle East and was at Chelsea from 2008-09.

Scolari was Portugal's most successful national team coach. He guided them to the final of the 2004 European Championship as hosts and the semi-finals of the 2006 World Cup, giving Cristiano Ronaldo his national debut and making him captain.

To help pay the salary of a World Cup-winning coach – and to prevent him from being poached by other clubs and countries which offered him contracts, including England – the Portuguese federation signed multimillion-dollar sponsorship deals, including with Nike and two Portuguese banks. Scolari, whose salary in Portugal was never made public, appeared in advertising campaigns.

Portugal's government has set up special investigative teams and increased penalties in an effort to crack down on tax evasion. The country needed a €78bn bailout in 2011 after high debts pushed it to the brink of bankruptcy.

In Spain, where authorities have also targeted tax evaders, officials have brought tax fraud charges against Lionel Messi and his club, Barcelona. Messi has denied any wrongdoing.