Terry McDermott has revealed that Craig Bellamy was hated at Newcastle and backed boss Graeme Souness' insistence that he should not return to the club.
Bellamy's fall-out with Souness ended on Monday with a loan move to Celtic.
And McDermott, who joined United as assistant to Souness last week, said: "People who have been here for 40 years have begged me not to let him back.
"I've never come across so much hatred and unrest over one person - what I've learned about him has astonished me."
Bellamy hinted he would like to return to Tyneside at the end of his loan, but McDermott sees this as unlikely.
He added: "I have no axe to grind with Craig Bellamy, but in the six days I've been here what I've heard means I don't want to meet the guy.
"You cannot have one player thinking he can run a football club."
McDermott bases his disregard for Bellamy not just on one major incident, when the player accused Souness of lying about the Welshman's injury before a Premiership match at Arsenal.
"Some of the things said by Craig, not just last week, but throughout his whole period at this club have been disgraceful," said McDermott.
He cited a phone message he claims was sent to a senior Newcastle player last week.
"That message alone should mean Bellamy can never play here again," McDermott concluded.