Chelsea's loan policy has come under further scrutiny after FIFA confirmed it had received a complaint from Fiorentina over Mohamed Salah's switch to Roma.
The Premier League champions allowed Salah, a January 2014 arrival from Bael, to join Fiorentina on loan in February and the Egypt winger impressed in Serie A.
Fiorentina have complained to world governing body FIFA after Salah joined domestic rivals Roma on a season-long loan this summer, alleging breach of contract. The claim is being investigated.
A FIFA spokesperson told Press Association Sport: "We can confirm having received a claim from the Italian club, ACF Fiorentina, against the English club, Chelsea FC, and the player, Mohamed Salah Ghaly, for breach of contract.
"The matter is still pending and being investigated."
Speaking prior to Saturday's match at Everton, Chelsea manager Jose Mourinho said about the complaint: "I'm happy that FIFA has time for other things in the middle of such great weather around them. I'm happy they have time for other things."
The club declined to comment, but technical director Michael Emenalo has defended the loan policy after 33 players left the club on a temporary basis this summer.
The reigning champions have allowed Juan Cuadrado -- bought from Fiorentina for £23.3 million in January -- to move to Juventus, while Victor Moses joined West Ham for the 2015-16 season shortly after signing a new four-year contract with the Blues.
Nathaniel Chalobah and Marco van Ginkel are among the other senior players now operating elsewhere, at Napoli and Stoke, respectively.
The remaining loanees are mostly members of Chelsea's youth academy and under-21 ranks but the club, who are not breaking any rules, have been accused of unfairly stockpiling players.
Emenalo insists the loan system has been put in place precisely to promote the development of talent.
He told Chelsea TV: "Sometimes we know there are players whose development is not finished, just like Victor, who we want to keep with our squad but who maybe needs to play more football to get to the level we think he can get to, because he is very, very talented."
The Nigerian admitted Cuadrado had been allowed to join Juve after suffering a crisis of confidence when he arrived at Stamford Bridge in the wake of Chelsea's 5-3 defeat at Tottenham.
At the same time, though, Egypt international Salah was sent to Fiorentina, for whom he would score nine goals, reinforcing Emenalo's faith in Chelsea's loan policy.
"Sometimes the timing is not right for them," he said. "For example we got [Juan] Cuadrado straight after a very difficult game at Spurs and we had to change our strategy for the rest of the season.
"That didn't suit the reason for which we had already gone to get him. So we felt it would be better for him to go and rediscover his confidence and he hasn't just gone to any other team... he's gone to Juventus.
"These players go to top clubs and when they get there they prove we don't recruit bad players, just like Salah did last season."