Peter Storrie and Milan Mandaric are facing a second charge of tax evasion while at Pompey.
The ex-chief executive and former owner have been charged as part of an investigation by City of London police and Her Majesty's Revenue and Customs.
The pair are already facing an earlier charge of cheating the public revenue, along with former manager Harry Redknapp, which relates to the transfer of Amdy Faye from Auxerre to Portsmouth in 2003 and a 250,000 payment into an agent's account.
On May 18, police charged Storrie with a second count of cheating the public revenue. Mandaric was charged with the same offence on May 21.
The Crown Prosecution Service refused to confirm reports that the new charge relates to a payment for former Pompey midfielder Eyal Berkovic into an offshore account, which HMRC claim was an attempt to avoid paying a tax bill.
A spokesman for CPS said the new charges are likely to be added on to the previous case which will be heard at Southwark Crown Court on Friday.
Mark Wilson, a director of Cartwright King Solicitors, issed a statement on behalf of Milan Mandaric.
It said: 'We are surprised and disappointed that the CPS has brought this charge against Milan Mandaric. It is without any foundation whatsoever and it will be very robustly defended.
'Mr Mandaric has devoted many years of his life to English football, first at Portsmouth and now at Leicester City.
'We are confident that he will emerge from these events fully vindicated and with his reputation for integrity and plain dealing completely intact.'
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