West Ham United have reported Sunderland to the Football Association for making an illegal approach for striker Demba Ba, an accusation the Black Cats have vehemently denied.
Ba, part of the Hammers side relegated from the Premier League, is the subject of a claim that the FA have confirmed the East Londoners have made against the side who defeated them 3-0 at Upton Park on Sunday.
On Tuesday afternoon a Premier League spokesman confirmed that Sunderland had been reported, saying: "We have received a letter from West Ham United. We will look into their complaint to see if there is a case to answer."
West Ham claim that Sunderland have breached the rules that govern transfers, specifically that they have acted outside of Section K of the Premier League rulebook. That states that a club cannot approach a contracted player at another club directly or indirectly without previously attaining written consent.
However, a spokesman for Sunderland has insisted that the Stadium of Light outfit had committed no such misdemeanour, saying: "Sunderland AFC is fully aware of the Premier League regulations pertaining to player recruitment.
"If we are interested in any player currently under contract with another club, we will speak directly to that club, in line with the regulations."
Newcastle United and Blackburn Rovers have also been linked to Ba, who only joined the Hammers in January after failing a medical at Stoke City. He had previously come to prominence playing for Hoffenheim in the Bundesliga.
His seven goals in West Ham colours, including two in their calamitous 3-2 defeat at Wigan last week, could not save the Upton Park men from dropping into the Championship.