Stade Francais players have gone on strike over a planned merger with rival Parisian rugby club Racing 92.
The clubs announced the surprise merger on Monday, saying it would create a new, stronger club that could enjoy a bigger fan base in the French capital.
Robins Tchale-Watchou, the president of the French players' union, said in a text message: "They're on open-ended strike."
Racing is owned by French property billionaire Jacky Lorenzetti, while businessman Thomas Savare is the current club president of Stade Francais.
In recent years wealthy businessmen have invested large sums of money into French rugby clubs, allowing them to sign top players from around the world.
Star players in the Racing 92 squad include New Zealand World Cup winners Dan Carter and Joe Rokocoko, while Stade Francais feature the likes of French international Pascal Pape and Italian captain Sergio Parisse.
Most of the players from both clubs voiced their concerns over the merger, which is widely seen by local media and rugby pundits as a takeover by Racing of cash-strapped Stade Francais.