The UK competition watchdog has ordered ABP Food Group and Dovecote Park's owner to keep their businesses separate while it examines the Irish meat group's investment in the UK red-meats supplier.
In an initial enforcement order, the Competition and Markets Authority said it had "reasonable grounds for suspecting" ABP and Extra Detail, Dovecote Park's parent, "have ceased to be distinct".
Last month, ABP acquired a minority stake in Extra Detail by buying out Benoni, which held a minority stake in the Yorkshire beef processor Dovecote Park.
At the time, Dovecote Park confirmed ABP has "taken a seat on the board of directors of Extra Detail and its subsidiary companies".
In a statement, the Waitrose supplier added: "Benoni, as a minority shareholder, will be supportive of the group's strategic direction, whilst maintaining the policy of acknowledging the current board and management team's independent ability and authority to grow and develop the Dovecote Park business."
The regulator is considering whether the deal has created a relevant merger situation and whether it has resulted, or could be expected to result, in a "substantial lessening of competition" in any UK ...