A Barcelona member has filed complaints with a French court and with the EU's European Commission with the aim of blocking any move by Lionel Messi to Paris Saint-Germain, according to documents seen by Reuters on Monday.
In the complaints, shared by the fan's lawyer, Juan Branco, the Barca member claims that French football authorities have failed to enforce their own financial fair play (FFP) rules in order to help PSG become a force in European football.
Barcelona, like its main LaLiga rival, Real Madrid, is fully owned by its subscription-paying members known as socios.
The FFP rules notably forbid top European clubs from paying their playing squads an excessive share of their total revenues, according to the member's complaints, which also state that the transfer of the 34-year-old to PSG would breach the code.
PSG and the Ligue de Football Professionnel did not immediately reply to requests seeking comment.
The EU commission confirmed receipt of the complaint.
"The Commission is assessing the complaint under its standard procedures," a spokesperson said.
Sam Boor, a senior manager in Deloitte's sports business group, told Reuters in April that European governing body UEFA has historically said a 70% wage-to-revenue ratio should be the upper limit for clubs to target. But he added that a number of large clubs might go past that figure and possibly even breach 100% in the short term.
Any transfer of Messi from Barcelona to Paris would constitute a distortion of competition with other national leagues, the complaints claim, and would be detrimental to Barcelona fans.
This distortion would affect the football market competition within the European Union, according to the complaint filed with the EU's executive body, and thus constitutes unlawful state aid.