Former owner Chainrai this week withdrew his offer to buy back Portsmouth, leaving the Pompey Supporters' Trust as the only remaining bidder.
But Hong Kong businessman Chainrai's company Portpin remains Pompey's biggest creditor and the PST have urged him to negotiate with them over the value of the club's ground, Fratton Park.
In an open letter to Chainrai, the PST said: "We now believe the only stumbling block to the trust achieving an acceptable deal is the difference over our valuation of the ground.
"Therefore we respectfully ask you to provide us with a valuation supported by a least two independent commercial valuers which we will then enable us to consider our position in the hope of responding with an acceptable offer."
Meanwhile manager Michael Appleton, who signed 10 players on one-month contracts on Thursday, has added another four loan signings to his squad.