The Scottish Football Association has been asked to provide information by FIFA about why former Rangers players have been blocked from continuing their careers elsewhere.
The SFA has been unable to process international clearance for the likes of Steven Naismith and Steven Davis, who exercised their right to leave the club under employment law when Sevco Scotland bought the assets of Rangers, following an objection from those in charge at Ibrox.
The matter is now in the hands of FIFA, who have written to Scotland's governing body seeking information.
One of the players, Kyle Lafferty, had been expected to make his competitive debut for Sion on Sunday but the Swiss club did not include him in their squad for their victory over Grasshoppers.
Lawyer Margaret Gribbon, who represents seven of the players, has asked the SFA to move quickly to ensure they are able to relaunch their careers.
Gribbon said: "Following the refusal of the SFA to issue players registrations, the new clubs have all referred the matter to FIFA.
"FIFA have now written to the SFA in each case requesting reasons why the players' registrations were blocked.
"It remains entirely unclear the facts and matters upon which Rangers oldco and Rangers newco rely in order to support their position that the players acted in breach of contract.
"Presumably they have made their reasons known to the SFA and if so, these have not been shared with my law firm, Bridge Litigation, who represent the majority of the players.
"FIFA have given the SFA seven days to respond but it is hoped that given the straightforward nature of the request the SFA will be in a position to reply sooner.
"We remain confident that FIFA will grant ITC (International Transfer Clearance) enabling the players to continue playing football with their new clubs."
Sevco chief executive Charles Green has argued that the players were in breach of contract when they joined other clubs but PFA Scotland believe their members were free agents.
Among the players to leave Rangers this summer, Naismith has linked up with Everton, Davis has gone to Southampton, Steven Whittaker has signed for Norwich and Jamie Ness has joined Stoke.
As well as Davis, Ness and Lafferty, Gribbon represents Allan McGregor, Rhys McCabe, Sone Aluko, and John Fleck.