Manchester United have warned Le Havre they will take action against them unless they stop repeating claims that the Red Devils offered financial inducements to Paul Pogba's family in order to lure the teenager to Old Trafford.
United have grown angry at the sustained assault by Le Havre, which came in the wake of a transfer ban imposed on Chelsea last week for a similar infringement of the rules.
Now Old Trafford officials have written to the French club, and made them aware in the strongest terms that they must either put up, or shut up.
"In response to the wholly unfounded comments widely reported in the media of Le Havre AC President, Jean-Pierre Louvel, Manchester United wish to categorically confirm that as a matter of club policy and in accordance with the applicable football regulations, we do not offer inducements to the parents of players who sign for the club such as monetary payments or the purchase of houses," said United in a statement.
"Manchester United have today written to Le Havre AC to put it on notice that action will be taken if such allegations are repeated in relation to the transfer of Paul Pogba."
Le Havre had claimed the matter was being referred to FIFA for their investigation, although as yet, the world governing body have not acknowledged receipt.
When the Pogba issue was first raised last week, United officials suggested that there was no contract for the 16-year-old to break, therefore the Red Devils could not be offering inducements to do so.
However, they have been annoyed by Le Havre's allegations of impropriety, which has prompted today's stinging outburst.
"Manchester United is entirely satisfied that the transfer of Paul Pogba has been conducted in accordance with the regulations set down by the world governing body, FIFA," the statement added.
"Manchester United is ready to defend any claim brought against it by Le Havre at FIFA. It is to be noted that all contractual documentation relating to the player's registration with the club has already been fully ratified by the Football Association and the Premier League."