FIFPro said in a statement that it would be neglecting its duty if it did not look at the impact on players' health of FIFA president Gianni Infantino's ambitious plans for a global Nations League and a revamped 24-team Club World Cup.
FIFA said that it had met representatives from several big European clubs on Wednesday as part of its "consultation process".
Infantino's proposed Club World Cup would involve expanding it to 24 teams — including 12 from Europe — and staging it every four years, starting from 2021, instead of annually as happens at present.
The Nations League would be a global version of the new competitions which are being introduced by UEFA in Europe and by CONCACAF in North and Central America and the Caribbean.
It would culminate in an eight-team knockout tournament -- effectively a mini-World Cup -- held every two years, also starting from 2021.
These new tournaments would be on top of existing competitions such as the World Cup and its qualifying competition, the European championship, Copa America and African Nations Cup.
"In the light of the current discussions, it would be remiss if FIFPro did not explore the impact of these proposals on players," FIFPro's European president Bobby Barnes told a meeting in Serbia, according to a FIFPro statement.
FIFPro said it recently surveyed more than 600 footballers for their views on the current match calendar, and is studying scientific evidence about the amount of recovery time players need between matches.
In an emailed statement to Reuters, FIFA said that its meeting on Wednesday allowed them "to observe a real interest for a complete reform of the Club World Cup and the development of a new model of competition that would benefit the entire football community around the world."
FIFA did not comment on which clubs had taken part. A report in the New York Times listed them as Manchester United, Barcelona, Real Madrid, Manchester City, Juventus, Paris St Germain and Bayern Munich.
Last week, European Leagues, an umbrella group representing Europe’s top football leagues, said they were in “firm opposition” to Infantino's plans.
(Writing by Brian Homewood in Bern; Editing by Toby Davis)
