• Club's position in tax haven angers rival clubs
• Promotion to Ligue 1 in doubt as wrangle continues
Monaco have launched legal proceedings against the French football authorities after rival clubs threatened to refuse the Ligue 2 champions admission to the country's top flight next season.
Having won promotion from the second tier last week, Monaco, in whom the Russian billionaire Dmitry Rybolovlev took a majority stake in December 2011, may be prevented from taking their place in Ligue 1 after rejecting other clubs' attempts to force them to pay tax.
Monaco have been playing in the French league for nearly a century, during which time the advantages gained from the principality's status as a tax haven have irritated other clubs, but never before has that led to such a confrontation. The cost cuts and tax hikes that French clubs now face seem to have intensified their ill-feeling towards Monaco, who have far greater purchasing power than anyone else in the league other than the Qatari-backed Paris Saint-Germain. Monaco have been linked with a string of top players, including Manchester United's Wayne Rooney and Atlético Madrid's Radamel Falcao, as well as the former Manchester City manager Roberto Mancini, all of whom would earn tax-free salaries.
In March the Ligue Professionelle de Football (LFP) voted to exclude Monaco unless the club moved its head offices to France to register with the country's fiscal authorities, an ultimatum that drew a furious reaction from Monaco.
The French Football Federation stepped in to mediate and eventually proposed that Monaco pay ¤200m (£170m) to be allowed to continue in the league, a supposed compromise that angered the club even further. It demanded that the FFF overturn the LFP's decision but the federation declined to do so and on Friday Monaco announced it "had no option" but to take the matter to France's council of state, the country's supreme court, claiming the LFP position "violates several fundamental principles of French and European law".
In a statement Monaco said: "The club intends to show that the decision of the LFP imposed on AS Monaco, forcing it to move its headquarters to France, violates several fundamental principles of French and European law, notably the principle of free movement, free competition, free access to sporting competitions, and also the Franco-Monégasque tax convention signed on the 18 February 1963."
The Uefa president, Michel Platini, an advocate of financial fair play, expressed surprise at the abrupt militancy of the French clubs. "I find it a little difficult to understand," Platini said after Wednesday's Europa League final. "It's as if French football always liked Monaco so long as they didn't win."