Eight senior players were understood to be in disagreement over unpaid salaries, though Luke Varney has since joined Leeds.
On Monday, Supporters group SOS Pompey handed over an open letter to the players at the club's training ground in a bid to persuade players to compromise on their wages and administrator Trevor Birch has said former owner Balram Chainrai could pull out of a proposed deal to buy the club if more players are not moved on.
And he told ESPN Soccernet: "Everybody, including the players, have been served notice that the club will close down on August 10."
Defender Tal Ben Haim and striker Kanu are among the players owed significant wages, with both players reportedly claiming around £3million in unpaid salary.
And Birch said. "The only way the club can be saved is if the players accept compromise deals.
"The Football League are in constant touch and know the situation, the PFA are also aware of it and are doing all they can to help.
"If the new owner does not take over the liabilities and guarantee £10million to football creditors then the Football League will not transfer its share and the club will go under.
"To save the club we are frantically trying to negotiate with players such as Kanu and Tal (Ben) Haim. We have offered Tal (Ben) Haim a substantial compromise which he has turned down, so it is difficult to negotiate.
"Perhaps he is playing a game of bluff. Perhaps he thinks we are bluffing that the new owner will save the club and still pay him or accept his liabilities going forward.
"We are now reaching a critical time, time is running out. I can only hope by serving notice that the club will shut down on August 10 that this will concentrate people's minds."
Pompey are due to face Plymouth in the Capital One Cup on August 14 before starting their npower League One campaign - for which they will face a 10-point deduction - against south coast rivals Bournemouth four days later at Fratton Park.
Professional Footballers' Association chief executive Gordon Taylor earlier described the situation as embarrassing for the game and said some players had been "unfairly intimidated", but agreed all parties had to agree to lose out if the club was to stay in business.
"It's about everybody getting in the same room, the players, the club, the administrators, the potential new owners and deal with the situation rather than looking at it separately," Taylor told Sky Sports News.
"If not there's no transparency as to how serious the situation is. If this club is going to survive we need everybody to have something - but not all that they are owed, otherwise everybody's just going to get nothing."
Taylor added: "There's been a bit of unfair intimidation on a few of the high earners. There's about eight I think that needed to go, to get settlements done and half of those have gone now.
"We've managed to get some security from the Premier League, they've been very co-operative on parachute payments, the Football League have told the owners they can't get all the money back that they put into the club originally, so they've got to take a hit."