Rival clubs are calling for an investigation by the Football League into Jorge Mendes' role at Wolverhampton Wanderers.

Mendes is a Portuguese agent whose clients include Jose Mourinho, Cristiano Ronaldo and ​Wolves head coach Nuno Espirito Santo, as well as a number of Wolves players. 

The club sit at the top of the ​Championship and look set for a return to the Premier League next season, but John Percy reports in the ​Telegraph that Championship rivals including ​Leeds, ​Aston Villa and Derby are all becoming concerned by the influence that Mendes has at the club. 

The agent first became involved in the club when Chinese conglomerate Fosun International completed its £30m takeover in July 2016. 

One club has even written to EFL chief Shaun Harvey, and the Football Association in order to raise the concerns they have with the agent's involvement. 

The letter highlights the FA's rules over third party interest in players, which states: “No club may enter into an agreement which enables any party, other than the club itself, to influence materially the club’s policies or the performance of its teams or players in matches and/or competitions.”

In the letter, a senior figure at the club urges the EFL to take a closer look at if Wolves are in breach of the FA rules through Mendes' involvement in player recruitment. 

Wolves staunchly deny that they are breaking any rules through Mendes' involvement, and point to the fact that the agent only acts as an advisor to the club, and is not in full control of the club's recruitment. 

The Football League have also confirmed that they are satisfied with Mendes' involvement with the club.

If Wolves do achieve promotion this season, then they will undergo vigorous owners and directors tests from the ​Premier League due to the league recently tightening the rules on third party interests.