France's National Union of Professional Footballers (UNFP) has threatened legal action against Paris Saint-Germain over the club's attempts to force Kylian Mbappe to accept a summer transfer.

Having already confirmed his decision not to trigger his contract extension beyond next summer, Mbappe has been warned by PSG that he will be sold immediately if he does not agree to a new deal.

To ramp up the pressure on Mbappe, PSG decided to leave the 24-year-old out of their pre-season squad, insisting to the French forward that his only options are to agree to leave or, preferably, sign an extension.

PSG's tactics have been blasted by the UNFP, who accused the Ligue 1 side of breaking French law by intentionally forcing Mbappe to accept poorer working conditions.

"These players - all of them - must enjoy the same working conditions as the rest of the professional workforce," the union said.

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"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.

"So, yes, the UNFP reserves the right to take civil and criminal action against any club that behaves in this way."

Mbappe's situation has attracted the interest of Saudi Arabian officials but 90min understands the Frenchman has his heart set on a move to long-term suitors Real Madrid.

Real Madrid sources have denied claims that an agreement has already been reached with Mbappe over a free transfer in 2024 although Los Blancos are planning to lure him over to the Santiago Bernabeu within the next 12 months.

PSG's asking price could prevent Real Madrid from making a bid this summer, with the Spanish side prepared to wait until January to make contact over a free transfer instead.

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This article was originally published on 90min as Kylian Mbappe: French players' union threatens legal action against PSG over pre-season snub.