Paris St-Germain have been accused of “moral harassment” after leaving Kylian Mbappe out of their pre-season tour of Asia, and the French footballers’ union said it could take legal action.
PSG’s all-time leading goalscorer has told the club he will not extend his contract, which has 12 months left.
The club want to sell Mbappe, 24, now to get a fee but Mbappe plans to stay until the end of his deal.
The France forward cost PSG £165.7m following his 2017 move from Monaco.
After Mbappe was left out of the PSG squad going to Japan and South Korea, a National Union of Professional Footballers statement said: “These players must enjoy the same working conditions as the rest of the professional workforce.
“The UNFP feels it would be useful to remind managers that putting pressure on an employee – via the deterioration of their working conditions, for example – to force them to leave or accept what the employer wants constitutes moral harassment, which French law firmly condemns.
“The UNFP reserves the right to take civil and criminal action against any club that behaves in this way.”
Mbappe has been a key player for PSG for six years, scoring 212 goals in 260 games, and winning or sharing the past five Ligue 1 Golden Boots.
He helped France win the 2018 World Cup and scored a hat-trick in the 2022 final defeat by Argentina.
He had been widely expected to join Real Madrid for free at the end of his last deal in 2022, but surprised nearly everyone by signing a new two-year deal at PSG.
After deciding he will not extend that deal any more, PSG believe he cannot remain part of their playing group.
Chairman Nasser Al-Khelaifi has said it is “impossible” that Mbappe will be allowed to leave for free in 2024.
Former Barcelona boss Luis Enrique replaced Christophe Galtier as manager of the Ligue 1 champions this summer.