FIFA has been warned of a threatened mass revolt and legal action by the world's footballers and leagues over its new men's Club World Cup amid welfare concerns.

A letter has been sent by global players' union FIFPRO and the World Leagues Association to FIFA president Gianni Infantino demanding the 32-team competition is not played as planned in June and July next year. Chelsea and Manchester City have qualified for the event, lined up for the United States as part of Mr Infantino's expansion of FIFA competitions.

The union fears this has congested the calendar and endangered the health of players. The leagues and players' union claims FIFA is being "inherently abusive" in adding games and urges Mr Infantino to use a council meeting next week to back down from its plans.

Sky News revealed in December concerns from players in England that they are being asked to play too many games with a threat of legal action against football authorities. That has now been stepped up to the global level ahead of key FIFA meetings in Bangkok, Thailand, next week.

FIFPRO Acting General Secretary Stephane Burchkalter and WLA counterpart Jerome Perlemuter wrote to Mr Infantino last week to warn legal advice has been commissioned ahead of potential action against FIFA to force them to resolve concerns. In a letter obtained by Sky News, they wrote: "We shall be compelled to advise our members on the options available to them, both individually and collectively, to proactively safeguard their interests." FIFA, the governing body for world football, has also expanded the World Cup for national teams - growing from 32 to 48 teams for the 2026 edition in North America.

The FIFPRO and WLF letter added: "FIFA has continually and consistently made unilateral decisions that benefit its own competitions and commercial interests, while negatively affecting national leagues and players. "Over a significant period, FIFA has ignored repeated attempts by leagues and unions to engage on this issue.

They added: "As a result of FIFA's recent strategy of expanding its own competitions, the calendar is now beyond saturation, to the point that national leagues are unable to properly organise their competitions, resulting in economic harm, whereas players are being pushed beyond their limits, with significant injury risks and impacts on their welfare and fundamental rights. "Leagues and players cannot simply be expected to 'adapt' to FIFA's decisions, which are driven by FIFA's business strategy.

"We have reached the point where this situation must immediately be addressed both from a procedural and substantive perspective." Read more:Sky Sports to show all EFL opening weekend matches for first timeUnion threatens legal action over increasing number of matches The Club World Cup is set to be staged every four years, replacing the little-regarded annual seven-team event that City won the final version of in December. After a three-team group stage, there will be another four matches up to the final.

Premier League chief executive Richard Masters recently complained about FIFA's lack of consultation over the addition of a new competition which follows UEFA expanding the Champions League to add matches from next season. "The feedback we have from players is that there is too much football being played," he said.

If their teams qualified for all the new competitions, some Premier League players could be required for more than 85 matches in some years for club and country. The congested fixture list leaves players with little space for rest and recovery with FIFA yet to grant union demands for a mandatory 28-day off-season break.

FIFA did not immediately reply to requests for comment today. But the global governing body has maintained that expanding the World Cup and Club World Cup is about growing the game globally and it has agreement within football from the European Club Association, with whom it has a commercial partnership.

The new Club World Cup is taking the quadrennial slot used up to 2017 for the now-defunct, eight-country Confederations Cup that served as a World Cup test event. While the seven-team annual version of the Club World Cup is going, December will see another FIFA event launch, with the Intercontinental Cup final contested in a single game by the UEFA Champions League winners.

FIFPRO and the WLA are urging FIFA to scrap the mini-tournament completely, although it is unclear where any legal action could be launched. Ultimately an agreement is needed with FIFA so clubs release their players from domestic duties for international and continental competitions..