Portsmouth manager Harry Redknapp was one of five men arrested on Wednesday morning in connection with alleged corruption in football.
City of London Police said the men - aged 69, 60, 55, 48 and 30 - were arrested on suspicion of conspiracy to defraud and false accounting.
Pompey have also confirmed that chief executive Peter Storrie was held.
A police spokeswoman said: "We can confirm that the men have been arrested on suspicion of conspiracy to defraud and false accounting.
"The arrests are part of the City of London police's investigation into football corruption."
Last year, the Premier League asked former Metropolitan Police Commissioner Lord Stevens and his company, Quest, to start an inquiry into hundreds of questionable transfer deals.
In June, Lord Stevens presented his final report, which highlighted concerns over 17 transfers and five Premier League clubs.
Officers then raided Newcastle United, Portsmouth and Rangers football clubs as part of the inquiry.
However, City of London Police have distanced their investigation from the inquiry.