The League have docked Pompey 10 points ahead of the forthcoming season and imposed financial restrictions.
This is because the way Portsmouth wanted to exit their current administration via a Company Voluntary Arrangement (CVA) did not have the 2010 creditors' approval.
"This is an urgent plea to creditors of Portsmouth City Football Club Ltd, the old company which entered administration in February 2010," read a statement on the club's official website. "The club need all such creditors to contact us with names, addresses and email addresses immediately as a matter of great importance.
"Time is of the essence as the fight goes on to save this great football club with 114 years of glorious history behind it. 2010 creditors are vital to the process.
"We need these details so that we can contact all 2010 creditors, inviting you to decide whether you are in favour of or opposed to the latest CVA proposal approved in June 2012 in order that we can lobby the Football League to reinstate the 10 points that have been deducted."