Manchester United have asked Fifa to consider punishing Chelsea over claims they induced John Obi Mikel to break a contract with the Old Trafford side.
Mikel signed a deal with Man Utd in April 2005
The two clubs are fighting over the rights to the 18-year-old Nigerian, with United writing to Fifa to complain, reports BBC Radio Five Live.
United want Fifa to consider imposing a transfer ban on the Blues as well as barring them from certain tournaments.
Chelsea say they are innocent and Fifa should be left to resolve the matter.
Mikel, who is currently playing in the African Cup of Nations, signed for United in April 2005 but later said he had been forced to put pen to paper.
He also claimed he wanted to join Chelsea instead - and admitted to the BBC again on Monday that Stamford Bridge was his preferred destination.
"Inside me I know where I want to go and I think Chelsea is the better place for me to be," he told Radio Five Live.
United made their complaint to Fifa in a joint submission with Mikel's current club Lyn Oslo.
The clubs claim agents acting on behalf of Chelsea attempted to induce the player to breach agreements he had made.
But in a statement released on Monday, the Blues expressed their anger that the letter to Fifa had been seen by the media.
"It is outrageous that private correspondence has been deliberately leaked in this way in an attempt to smear Chelsea's name and, more importantly, to undermine an active Fifa process and pressurise Mikel," said the statement.
"For the record, Chelsea informed Fifa at the time that these allegations were without foundation.
"As far as Chelsea is concerned this whole issue is a matter for Fifa, which is the correct and most competent authority to decide on it."
Fifa also plan to investigate claims Mikel received death threats in the midst of the row, although there is no suggestion they came from Chelsea.
Mikel denies receiving threats, but Five Live has three sworn affidavits from employees of Lyn claiming the teenager was threatened over the telephone.
Fifa say they are waiting for notification that formal legal proceedings in Norway are closed before making a ruling.