A number of Championship clubs have reportedly voiced concerns to the Football League and Football Association over Wolverhampton Wanderers' financial affairs.
The second-tier pacesetters have used their strong connection with agent Jorge Mendes to bring in a string of star players to spearhead their push for promotion.
According to The Mirror, though, rival clubs have "voiced their dissatisfaction" and want an investigation to be launched looking into Wolves' transfer dealings.
Pressure is said to be building on the governing bodies to explore the signings of players such as Ruben Neves from Porto and loan recruit Diogo Jota from Atletico Madrid.
A club insider is quoted by the publication as saying: "If Wolves have brought in players such as Neves for £15m, he must be being paid as a player worth £15m should be.
"It's the same with others they have brought in from Monaco, Atletico Madrid and Valencia. None of these players would come on the cheap. Something doesn't add up."
Wolves, who insist that they have complied with financial fair play laws, find themselves 10 points clear of third-placed Aston Villa heading into the final stretch of the campaign.
