The mayor of Liverpool has asked police to investigate whether any "fraud" has taken place surrounding Ross Barkley's transfer from Everton to Chelsea.
Joe Anderson has written to the heads of the Football Association (FA) and Premier League following the 24-year-old England midfielder's £15m move.
The "circumstance" of the deal "warrants serious investigation", said lifelong Everton fan Mr Anderson.
Merseyside Police said Mr Anderson's letter "is currently being considered".
In the letter, on his official headed notepaper, Mr Anderson expressed concern about the size of the transfer fee paid by Chelsea for Barkley.
The Premier League champions had reportedly agreed to pay £35m in the summer, only for Barkley to pull out of the move to Stamford Bridge at the last minute.
Noting that Barkley did not play "a single minute for Everton" in the time between these two negotiations, he said the player has seen "a decrease in value of more than one million pounds a week".
He claimed: "At best, this represents a very poor deal for Everton Football Club.
"At worst, it could be seen as a deliberate attempt to drive down a player's value in the transfer market so as to benefit the player, his agent and the buying club," Mr Anderson said.
In the letter, Mr Anderson tells FA chairman Greg Clarke and Premier League executive chairman Richard Scudamore that he feels "it is right that the public receive an assurance on this matter".