Portsmouth administrator Trevor Birch has warned the club will go out of business on August 10 unless an agreement can be reached over the wages of their senior players.
Eight senior players were understood to be in disagreement over unpaid salaries, though Luke Varney has since joined Leeds.
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 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.
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.
"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."