Portsmouth administrators PKF have confirmed to BBC Radio Solent that senior players will leave Fratton Park as they look to reduce their wage bill.
With Pompey in administration, most of the club's players are only on short-term deals which expire this month.
One of those who is leaving is full-back Jon Harley, who confirmed on Twitter that his deal ending on 15 January will not be renewed.
However, defender Gabor Gyepes, 31, has signed a new one-month deal.
Gyepes's future with the club had been in doubt after he admitted he would leave if he found a "better option" before his previous contract expired this month.
But the Hungarian, who is Portsmouth's highest goal scorer still remaining at the club with four goals, has committed himself to the side for the short term.
Portsmouth have also decided to recall 18-year-old left-back Dan Butler from his loan spell at Havant & Waterlooville, which may help lessen the blow left by Harley's departure.
Caretaker manager Guy Whittingham has no money to buy players so only free agents or loanees can be signed.