Ticketus have formally launched legal action against Craig Whyte over money owed to them by administration-hit Rangers.
Majority shareholder Whyte has revealed he gave personal guarantees to the investment firm over capital issued to the club on the basis of future season ticket sales.
Documents from a previous court case showed Ticketus had made two payments to Rangers, one in May last year and one in September, which were worth more than £30million when VAT was added.
The initial payment, worth £24.4million in total, was used by Whyte to pay off the club's bank debt.
With money from ticket sales last season clawed back, Ticketus are owed £26.7million, according to a report by administrators.
A statement from the London-based firm said: "Ticketus today confirms that it has made demand pursuant to the guarantees provided by Craig Whyte and The Rangers FC Group Limited, formerly named Wavetower Limited.
"In addition, demand will be made against Liberty Capital Limited.
"These guarantees form part of the additional protection built into the ticket purchase agreement that Ticketus made with the club in May 2011. As previously stated, Ticketus will claim upon these guarantees to recover any potential shortfall in monies owed to Ticketus by the club."