United are second-bottom of the Barclaycard Premiership and are desperate to keep their best players as they fight for their Premiership lives.
Leeds chief executive and acting chairman Trevor Birch claims Leeds do not need to sell during the transfer window.
However, he told The Sun: "If you have a player who doesn’t want to play for the club, he is going to mope around. That can be disruptive.
"Of course, you can always say to him he has to stay put. But if the player himself wants to go, history would say you are in some difficulty.
"I just hope all our players want to stay at Elland Road and help us get out of the situation we are in.
"Our stated policy is that we don’t have to sell during the transfer window. There is interest in Viduka but I have already made it clear he is not for sale.
"We don’t want to sell anybody unless the player puts in a transfer request. At this moment, we are assuming all our players want to stay."