The 20-year-old Frenchman said over the weekend that he is happy on Wearside, but has rejected the contract offer put to him by Sunderland.
Wilkinson said: "The transfer window opens in January, speculation is rife, David Bellion is out of contract and at the moment he has chosen not to accept what he has been offered here.
"There is talk of Manchester United being interested but, again, as far I`m concerned, David Bellion is very important to our success here at the moment and I have to look after the interests of Sunderland Football Club."
With Bellion`s contract due to expire in the summer, The Black Cats would be entitled to a fee even if he moves on as he is under 24.
However, the amount they could command for the former Cannes man would, in all probability, in no way reflect his potential.
The latest development is sure to alert the likes of Red Devils boss Sir Alex Ferguson and his fellow Knight, Newcastle chief Bobby Robson.
Wilkinson stressed that he needs to 'look after the interests of Sunderland' and this could see him accept a bid from a rival club in January, if there is no hope of Bellion inking a contract.
However, with Wilkinson commanding a lot of respect in the Stadium of Light dressing room, he may choose to fend off any bids in the hope of persuading Bellion to commit his future to The Black Cats.
Meanwhile, Sunderland defender Cliff Byrne's loan spell at Scunthorpe United has been extended by a further month.
The centre back impressed during his first month at Glanford Park, and Wilkinson has now agreed to let him stay until the end of January.
The news means that the Irishman should figure in the Iron's re-arranged FA Cup tie with Carlisle United on Monday.
