Leeds United reportedly face the prospect of being hit by a transfer embargo due to the ongoing contract dispute with former midfielder Cameron Stewart.
The 24-year-old accused the Whites of failing to pay up money they owed him after withdrawing from a deal last season.
It has now been claimed by The Mirror that the PFA will ask the Football League to prevent Leeds from signing any more players this summer if they fail to hand over £800,000 - the amount awarded to the Manchester United academy product at a hearing in May.
Stewart, who is now plying his trade at fellow Championship club Ipswich Town, moved to Elland Road on an emergency loan deal from Hull City midway through last season, but the Yorkshire outfit pulled out of a permanent deal following issues with paperwork.
