Portsmouth have warned AEK Athens they must pay 1million euros (£820,000) to land Papa Bouba Diop.
It is believed the Greek side have agreed personal terms with the midfielder and aim to take up the final year of his contract instead of paying a fee.
But Portsmouth's administrator Andrew Andronikou insists the Greek outfit must meet the Championship club's valuation or risk missing out on the player.
He told The News: "Athens are making noises and I have been in direct contact with them.
"They know our position and they know they have to write a cheque. Unfortunately that has not happened yet.
"Diop is available for 1million euros and if they want him they will have to pay that amount. We have absolutely no intention of giving him away."