Benfica president Luis Filipe Vieira has been placed under house arrest until he pays bail of three million euros (£2.5 million).
Vieira and three other men are being investigated as part of Operation Red Card for possible fraud, money laundering and tax fraud.
Defence lawyer Manuel Silva told reporters that the president of Portugal’s most successful football club denies any wrongdoing.
Benfica is not under investigation.
The 72-year-old has run the club since 2003.
Former star Rui Costa, who was a club vice president, has taken over its management.