Hartlepool have accused Fulham of "underhand" tactics over the signing of youth player Luca Murphy, and insist they will "vigourously pursue" an agreed amount of compensation.
The non-league club claim a fee was agreed with the Whites as a condition of the player going on trial with them in January - but Fulham subsequently said the player was not good enough to join.
Murphy's behaviour back at Victoria Park worsened after his return and he was released, according to Hartlepool chief executive Mark Maguire, and chairman Raj Singh believes "it is pretty clear" he was encouraged to act up to help orchestrate a move.
Fulham, who have so far not responded to Sky Sports News' request for comment, announced the signing of Murphy - a 17-year-old centre-back - on a two-year deal on Friday.
And Pools chief-executive Maguire said: "We agreed a figure with Fulham in good faith in January and allowed Luca to travel to London to get to know the facilities with a view to signing.
"We were then given a list of reasons why the player wasn't good enough to sign for them and they ended their interest.
"Subsequently, Luca's behaviour deteriorated to the extent that it was no longer appropriate to have him around our youth team, but when he left us both he and his agent were made aware that we reserved our right to pursue compensation.
"It is a sad irony that less than a year after Fulham fans were amongst those contributing to a fund to help save Hartlepool United from oblivion, their club is acting in such a way to secure the services of a player in whom Hartlepool United has invested since he was nine-years-old.
"The behaviour of the player, his agent and Fulham FC leaves a lot to be desired, and that is an understatement. We have written to Fulham to explain our position and will now pursue compensation through the appropriate channels.
"Hartlepool United will continue to invest in youth development, which is at the heart of what we do, but we need the support of the football authorities to protect us against this kind of underhand behaviour."
Pools chairman Raj Singh said: "As I suggested in my programme notes on Saturday, we have been expecting something like this to happen and, frankly, it makes you strongly question the value of investment in youth if we are exposed to behaviour like this from clubs, players and agents.
"Hartlepool United nurtured this lad from nine-years-old and it is pretty clear that he has been encouraged to behave in a manner which orchestrates this move.
"Whether that is to save a few thousand pounds for a club earning over £100 million, or to earn an agent a fee, we will probably never know.
"What I do know is that we will protect ourselves and, whilst we won't give up on youth development, we will make sure we know who we are dealing with and who represents them.
"It will also unfortunately mean that we will never again trust a club with the courtesy we showed to Fulham and we hope that we will be protected by The FA in this regard."
Fulham's transfer of Jean Seri from Nice is currently being investigated in France amid accusations the combined transfer fee was manipulated in order to undervalue Seri.