LaLiga last month struck a €2.7 billion ($4.3 billion) deal with CVC that will see the private equity firm acquire 10 per cent of the commercial business. The other 90 per cent of the investment was earmarked to boost cash-strapped clubs in the top two tiers of Spanish football as they deal with the financial impact of the COVID-19 pandemic.
Madrid and Barcelona allege the agreement impacts all clubs' audiovisual rights for the next 50 years, with Los Blancos announcing legal action, including against LaLiga president Javier Tebas, last month.
The deal was overwhelmingly passed by the LaLiga assembly on 12 August, yet Barca, Madrid and Athletic still refuse to accept it, while the Spanish Football Federation (RFEF) labelled the agreement as "totally illegal".
In a statement released on Saturday (AEST), the trio of top-flight clubs made clear its intentions to contest the resolution, after what it describes as a "highly irregular and disrespectful process".
The statement read: "Barcelona, Athletic Club and Real Madrid announce that they have challenged the agreement adopted by the LaLiga assembly on 12 August, 2021, relating to the operation between LaLiga and CVC, as it being an agreement that infringes the applicable rules set out (and in particular, amongst others, the Royal Decree Law 5/2015), and it was adopted as part of an highly irregular and disrespectful process toward with the minimum guarantees required to those purposes, especially faced with an operation of such importance and longevity."
LaLiga boss Tebas claimed that Barca would have been able to keep Lionel Messi had it agreed to sign up. Owing to the club's serious financial issues, the Argentina superstar was unable to sign a new contract and instead joined Paris Saint-Germain.
Tebas also insisted CVC is investing to develop the league, rather than salvage the finances of Spanish clubs.
"CVC was interested because of how we have developed, without help from [Real] Madrid or Barca. CVC has not come here to bail us out – it is not here because of the pandemic," he said.
"Only 15 per cent of the money can be used to pay off debts, 70 per cent is for investment in infrastructure. So it is not here to bail out Spanish football, but to help build a stronger league."