Spanish football’s leading financial expert, Gay de Liebana, has told newspaper AS that he agrees with growing concerns that Real Madrid are hiding the true nature of their debts, says ESPNFC's Dermot Corrigan.

Per Corrigan's article, club president Florentino Perez maintains that the club's current levels of debt amount to a manageable €90 million. However de Liebana and fan groups believe that the true figure is well in excess of €500 million.

The economist believes that, should the debt levels continue to rise, the club would have no option but to become a limited company.

Per Corrigan, de Liebana is quoted as saying:

Madrid’s debt is, effectively, €541 million. That represents 64 percent of its total liabilities. It is a very high debt and there is a problem. The short-term debt, which is €338 million, is higher than its current or liquid assets, which are €239 million. So there is €100 million in negative working capital.

It is true that Madrid has important cash on hand—€156 million at the end of the season. But you cannot abuse negative working capital. If you look at Arsenal or Bayern, two reference points in financial management, their working capital is positive. Madrid has homework to do.

The warnings come just a day after former director of football Jorge Valdano proclaimed the club was forced to sell Mesut Ozil to Arsenal due to the level of debt and their purchase of Gareth Bale, per the Daily Star's Jack Wilson.

Valdano's quoted figure of €541 million matches the projection of de Liebana and should worry fans of Madrid.

In his assessment, de Liebana was brutally honest as to the Spanish giants' impending issues.

The two big clubs in Spain have already effectively maximised their TV revenues by taking such a large share of the La Liga pot. And a lack of investors make Real Madrid's planned €400 million stadium improvements difficult without a large amount of money borrowed off the banks.

He also, pointedly, criticises the lack of success that the team have achieved under the Perez era—despite over €700 million in spending on new players. This all comes in the week following Jose Mourinho's comment that he coached the greatest Real Madrid side in history, per Goal.

Since the second Perez term began in 2009, Madrid have won just one league title and one Copa del Rey—a relatively barren spell for the club as they continue to chase their 10th European Cup triumph.

Running Madrid has always been a complex balance between levelling the books and ensuring the club's demanding supporters are appeased with big-name signings.

After all, it was under Perez in 2001, at the height of the free-spending Galactico era, that the club sold their training ground to municipal authorities—a deal that has brought scrutiny over possible state aid, per Bloomberg.

Unless Perez is telling the truth and Madrid's debts are much lower than anybody outside the club estimates, big decisions will be needed to ensure the club evade a period of financial crisis at the Bernabeu in coming years.

High spending and a lack of consistent major honours now sees the club walking a financial tightrope. If de Liebana's figures are accurate, Madrid's levels of debt are on the verge of becoming unsustainable.