Lorient vice-president Alex Hayes has described Sunderland's conduct as "scandalous" after Lamine Kone's move to the Stadium of Light fell through.
Sunderland boss Sam Allardyce confirmed on Thursday the club would not be pursuing a deal for the Ivory Coast international, despite him travelling to England to discuss personal terms and undergo a medical.
Allardyce said on Thursday: "The Kone deal has broken down. It's nothing to do with a medical or anything like that, the negotiations just broke down and it didn't happen."
Hayes took a dim view of the situation and claimed Sunderland had tried to change the deal.
He told Le Telegramme newspaper: "It's quite scandalous.
"We gave Sunderland our consent last Tuesday. Lamine left the next day to have contract talks but the player warned us there were problems in negotiating his contract.
"Because of the holidays it dragged out until Monday. They [Sunderland] tried to change the deal.
"Lamine called me to ask if he could return to Lorient and I told him 'with great pleasure'."
Kone's trip to England meant he missed Lorient's Coupe de France clash with Tours, while he is unlikely to play in the Ligue 1 fixture against Rennes this weekend.
King added: "Our defensive pillar was lost for the cup tie and the Rennes derby, for nothing. Meanwhile Sunderland have negotiated [to buy] a player from Bayern Munich [Jan Kirchhoff]."
