The property tycoon is in talks with Pompey owner Sacha Gaydamak over a figure for the south-coast club, with paperwork for the fit-and-proper-person test having already been submitted to the Premier League.
Al Fahim's advisor Ivo Ilic Gabara told the Portsmouth News: "Due diligence has been completed. We are now making a final commercial assessment with information obtained through the due diligence process."
He added: "We will then sit down and negotiate a final price based on how much both parties think the club is worth.
"We have never said the entire deal would be completed in July. We said all along we expected due diligence to be completed in such a time frame - now that has happened. I cannot possibly say when a final fee will be agreed. The deal is not closed until it is closed, like any financial transaction.
"But both parties want it completed as soon as possible to proceed in a good manner."
Pompey are hopeful the proposed deal will be rubber-stamped well ahead of the start of the new Barclays Premier League campaign in mid-August.