Barcelona are allegedly threatening to launch criminal proceedings over the contract extension that Frenkie de Jong signed in 2020.
Speculation surrounding the 25-year-old's future continues to dominate the transfer market as Manchester United continue their long and arduous bid to sign him.
The Red Devils are believed to have reached an agreement with Barcelona for a £63m deal to sign De Jong, which could reach up to £71m with add-ons.
However, Erik ten Hag's side, as things stand, have not been able to convince the Netherlands international to leave Camp Nou amid a bitter dispute over his salary.
While Barcelona's financial toil deepened during the COVID-19 pandemic, De Jong was one of several players to agree to defer his wages, and he is now seeking to be paid the outstanding monies.
De Jong is supposedly owed as much as €18m (£15.1m) by the Catalan giants, who are determined to offload the ex-Ajax man in order to help balance the books, but he is refusing to budge on his stance.
Barcelona could now take another dramatic turn in the situation, though, as The Athletic claims that the Blaugrana have broached the idea of criminal action over De Jong's contract.
The midfielder initially signed a five-year deal at Camp Nou upon his arrival in 2019, and a two-year extension was agreed in October 2020 under Josep Maria Bartomeu's reign.
Bartomeu and his board stood down in 2021 as Joan Laporta returned to the helm, and Barcelona allegedly received a letter from the club last month claiming to have found proof of criminal activity in his 2020 renewal.
The report claims that Barcelona then want De Jong to agree to annul his existing terms and revert to the deal he first signed at the club in 2019, with the previous board accused of the wrongdoing.
Bartomeu has always insisted that he acted within the law during his time in charge at Barcelona, with La Liga and the relevant authorities giving their blessing for De Jong's new deal.
Clement Lenglet, Marc-Andre ter Stegen and Gerard Pique extended their contracts at the same time as De Jong, but it is unknown if the trio have also been threatened with legal consequences.
Barcelona - who have spent in excess of £100m to sign Raphinha, Jules Kounde and Robert Lewandowski, all of whom are yet to be registered with La Liga - declined to comment to The Athletic over the report.
De Jong has 13 goals and 17 assists to boast from 140 competitive games for Barcelona and scored for the Blaugrana in Saturday's 6-0 thrashing of Pumas in the Joan Gamper Trophy.
Laporta recently affirmed to reporters that he wants the Dutchman to stay at the club, saying: "Frenkie de Jong is a Barca player of great quality and we want him to stay. With him and his teammates, we have a very powerful midfield. He has offers, but we want him to stay and he wants to stay too."
Chelsea have been tipped to hijack Man United's move for De Jong, but Thomas Tuchel recently played down hopes of his side spending big on a new midfielder this summer.
