The Scottish Premier League are to investigate the alleged non-disclosure of payments made to players by Rangers.
The probe will examine whether further payments were made in addition to main contracts and if SPL rules and regulations were breached.
The Scottish Football Association were already aware of the claims, made by former director Hugh Adam.
Adam said that some payments were not included in official contracts that were registered with the SPL and SFA.
A brief statement from the SPL said: "The SPL Board has instructed an investigation into the alleged non-disclosure to the SPL of payments made by or on behalf of Rangers FC to players since July 1, 1998.
"SPL rules F1, G1.1 and G1.5 give the SPL Board wide powers of investigation into potential breaches of the SPL rules.
"SPL rules D9.3 and D1.13 impose a prohibition on players receiving payments for playing football or participating in an activity connected with football except where such payments are made in accordance with a form of contract approved by the SPL and require that all such contracts are submitted to the SPL within 14 days of being entered into."
In a Daily Mail interview, Adam claimed that Ibrox directors were aware of the widespread use of an Employee Benefits Trust scheme.
A high-profile first tier tax tribunal will deliver a verdict soon on the EBT arrangement deployed by Rangers under the stewardship of former owner David Murray.
Regardless of that ruling, any 'off-the-books' payments to players would be a clear breach of SPL and SFA statutes.
"We will be looking into it and taking whatever action is necessary," said SPL chief executive Neil Doncaster.
"We'll be dealing with the administrators at Rangers to establish the facts, to establish whether there were any payments that were made that were undisclosed at that time.
"If there are, then we'll take that forward.
"Our role here is to apply the SPL rule book.
"We'll conduct the investigation as quickly as we can."