Sporting Lisbon claim Doyen Sport threatened to the "cause problems with the in the club's academy" unless they agreed to sell defender Marcos Rojo to Manchester United.
Doyen own 75% of the Argentine defender's contract after financing three quarters of the player's transfer fee when he joined the Portuguese club from Spartak Moscow in 2012.
The Malta-based investment group said on Wednesday they have placed no pressure on Sporting to sell Rojo this summer, but added they may be forced to take legal action to ensure they are compensated for their part in the player's move two years ago should he move to United this summer.
Sporting have since announced plans to cancel their agreements with the group in light of these developments. But in an extraordinary statement released by the club, Sporting claim executives representing the Doyen group travelled to the Estadio Alvalade posing as officials from an unnamed club - thought to be United - in an attempt to conclude a deal for Rojo.
The claim they informed Rojo's agent – in strict confidence – they would sell the 24-year-old should they receive an acceptable offer this summer. But following Sporting's change of heart Doyen would appear to have taken it upon themselves to force the move.
"Following the rejection of the proposal and a request for a meeting, that same club made a surprise visit to Estádio José Alvalade, with that club thereby being received out of courtesy by an member Sporting's Board of Directors," Sporting statement read.
"Subsequently, Sporting became aware that Doyen took part in the resulting meeting, namely by convincing the member of Sporting's board of Directors that the person in question was as member of the visiting club and not in fact the CEO of Doyen. The situation was masked to such a degree that the person in question did not at any time speak in Portuguese, communicating at all times in the language used by the visiting club."
In their attempt to illustrate their extent of Doyen's desire to influence Rojo's future, the statement goes onto reveal an incident where the group's CEO Nelio Lucas threatened to further disrupt the club.
"In light of the seriousness of statements being made and falsities being communicated, we have been forced to reveal that at the beginning of the 13/14 season, that same CEO sent various abusive text messages to the president of Sporting, including one which stated in capital letters: "MARCOS ROJO IS GOING TO THE [FOREIGN CLUB]" and that "IF YOU DO NOT LET HIM HE WILL BEGIN TO CAUSE PROBLEMS IN THE ACADEMY".
Should Sporting's claims be true, they are in direct violation of Fifa's regulation stating that third party investors such as Doyen are barred from influencing transfer activity, in addition to the group's own mandate that states: "The company's contracts are transparent, clear and unlike other competitors, advocating complete independence of the clubs in decisions."