The lawyer behind football's landmark Bosman ruling has written to the Football Association to demand an inquiry into Jean Michael Seri's transfer to Fulham from Nice.
The Ivorian midfielder joined the Premier League club with French left-back Maxime Le Marchand for a combined fee of £25million this summer.
According to French reports, the breakdown of that fee was approximately £15million for Le Marchand and £10million for Seri, despite the latter being better, younger and having longer on his contract.
Previously linked with Barcelona, Seri has already started legal proceedings in France against Nice, as he claims the club undervalued him in order to avoid paying a bonus. Le Marchand's value, on the other hand, was overstated.
Nice have denied this claim, but it has now emerged that Seri's former clubs in the Ivory Coast and Portugal believe they have been deprived of sell-on payments by the alleged manipulation of the combined fee.
Belgian lawyer Jean-Louis Dupont, who revolutionised the transfer market in 1995 when he won a case for Jean-Marc Bosman, is representing the two clubs in the Ivory Coast, Centre Domoraud Cyrille and ASEC Mimosas.
He has written to the FA's chief investigations officer David Matthews on Monday to ask English football's governing body to investigate the allegations.
"In the proceedings that take place in France, Mr Seri has decided to direct his claim directly against OGC Nice," wrote Dupont.
"Centre Domoraud Cyrille and ASEC Mimosas believe however that this manipulation could not have taken place without a particularly active role of Fulham FC.
"As you know, pursuant to the relevant FIFA rules, it is Fulham FC that is the debtor of the solidarity fees towards the two African training clubs.
"Could you please let us know with due clarity if you are in a position to investigate these allegations and what could concretely be expected from your intervention?
"As you will understand, our clients are convinced that your intervention is not only absolutely necessary for them but also for the FA, if the FA is serious about complying with its ethical (and legal) commitments."
Fulham, who are bottom of the Premier League after just two wins in 14 games, have declined to comment, but it would appear they wanted the pair as they have both appeared regularly this season.