Luis Filipe Vieira, who suspended his duties as president of Benfica last week after being detained as part of an investigation into alleged tax fraud and money laundering, has resigned, the Portuguese club said in a statement.
Vieira, who ran the club for 18 years, said in a letter to the chairman of the board that he was no longer in a position to carry out his duties after his arrest.
"The directors of ... Benfica appeal for [fans] to unite around their common objectives and the safeguarding of the higher interests of the club," Benfica said in a statement on their website.
Vieira, 72, was taken into custody on July 7 for questioning over deals worth more than €100 million ($118m) that may have caused large losses to the state and several companies, public prosecutors said.
A court ruled on July 10 that Vieira would stay under house arrest until a €3m bail was paid and ordered him to hand over his passport, giving him 20 days to pay the money.
Rui Costa, formerly vice-president of Benfica, took over last Friday as president after Vieira's suspension. It is not yet known whether he will remain in the position permanently following Vieira's resignation. The board will meet on Friday to finalise the leadership changes.