An announcement on the London Stock Exchange claims that former Rangers chief executive Charles Green has been reported to the Serious Fraud Office.
The notice was posted on Wednesday by Worthington Group PLC, which recently purchased a share of a company owned by former Rangers chairman Craig Whyte. The allegations are linked to the conduct of Green and commercial director Imran Ahmad.
Worthington Group say that the alleged "information" was uncovered during its purchase of a 26% stake of Whyte's company Law Financial.
It said: "During the course of the company's due diligence process, relating to its purchase of a stake in Law Financial, information has been discovered relating to the conduct of Mr Charles Green and Mr Imran Ahmad. This has today been reported to the Serious Fraud Office."
The group claims Sevco 5088, which bought all of the business and assets of Rangers when the club entered administration last year, is a subsidiary of Law Financial.
However, a statement released on Rangers' official website on Wednesday states that Sevco 5088 is a defunct non-trading company, which is "not an active subsidiary of the Rangers International Football Club".
Green stepped down from his position as Rangers chief executive last week after alleged racist comments made in a newspaper interview and speculation that he had closer links to Whyte than he had let on.
Information from the Press Association was used in this report.