Messi, who put pen to paper on the astronomical deal back in 2017, has been left seething after details of his hefty salary were revealed in El Mundo on Sunday.
The Spanish outlet’s report claims he is the highest-paid sportsman of all time, taking home an eye-watering salary of £123million per year at Barca.
But according to Catalan radio station RAC1, Messi is readying legal action against five individuals he believes are behind the leak.
The report states those individuals, whom Messi knows had access to the contract, are: Former Barca president Josep Maria Bartomeu, CEO Oscar Grau, interim president Carles Tusquets, ex-vice president Jordi Mestre and legal chief Roman Gomez Ponti.
It is believed he is also prepared to sue El Mundo over their publication of the contract leak.
The potential legal dispute marks yet another crack in Messi’s relationship with Barca, having submitted a shock transfer request at the Nou Camp last summer.
In the end he agreed to stay and see out the final year of his lucrative contract, meaning clubs can snap up the Ballon d’Or legend on a free transfer this summer.
Messi felt he was free to walk away from the Catalans last summer, disputing one of the clauses inserted into his contract by Bartomeu.
The ex-president has already denied any involvement in the leaking of Messi’s contract details following his own acrimonious departure back in October.
He told TV3: “It’s completely false. This is a very serious issue because it’s completely illegal to leak any professional contract to the media.
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“It’s easy to make accusations but this is not a joke and it’s going to end up in court.
“Messi deserves everything he earns, be that for professional or commercial reasons. Without the pandemic, Barcelona would be more than capable of paying those numbers.”