The former West Ham hitman, speaking exclusively to Football Insider, claims the club is currently “a mess”.
On 2 November, The Athletic reported Newcastle were in negotiations with Unai Emery, their number one target to replace Steve Bruce.
However, those talks collapsed and Football Insider revealed at lunchtime today that Newcastle are now in advanced talks to appoint Eddie Howe.
McAvennie claims United’s new owners have to fire whoever is speaking to the press as it makes the group look “amateurish”.
“It’s not a good look for the new owners,” McAvennie told Football Insider correspondent Ben Wild.
“Whoever is briefing the press is doing a horrible job. It’s a mess.
“It sounds like Villarreal are annoyed and it will never help to see loads of reports coming out about your manager.
“I get you have to get the decision right. But if I was them, I would find whoever is speaking to the press and get them out the door.
“It’s bad now and all they are trying to do is appoint a manager.
“Imagine what it will be like when they are trying to sign players.
“It just makes them look amateurish and that’s the last thing Newcastle need.”
They are next in action against Brighton on Saturday evening.