Cristiano Ronaldo said he believes the Glazer family, which owns Manchester United, sees the team as a "marketing club" and that they don't care about football.
The comments came during an explosive interview that first aired on Sunday in which Ronaldo told Piers Morgan that he felt betrayed by Man United and had no respect for first-year manager Erik ten Hag.
The Glazers have been criticised by United fans for not investing enough in the team, who have not won a trophy for five years, with Ronaldo adding that he had never talked to the American owners.
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"The Glazers, they don't care about the club or professional sport. Manchester [United] is a marketing club," Ronaldo said to Morgan on TalkTV. "I want the best for the club. This is why I came to Manchester United and why I love the club.
"But you have some things inside that don't help [us] reach the top level as [Manchester] City, Liverpool and even now Arsenal. A club with this dimension should be top of the tree in my opinion and they are not, unfortunately."
Ronaldo added in the interview that he felt it would be difficult for United to be at the top of the game in the next two to three years.
On Monday, sources told ESPN that United were furious with Ronaldo for some of his accusations, while disputing assertions that he was being forced away from Old Trafford in the summer and that the facilities at their Carrington training base had not been updated since he left for Real Madrid in 2009.
United issued a statement on Monday saying: "Manchester United notes the media coverage regarding an interview by Cristiano Ronaldo. The club will consider its response after the full facts have been established.
"Our focus remains on preparing for the second half of the season and continuing the momentum, belief and togetherness being built among the players, manager, staff, and fans."
The friction between Ronaldo and Ten Hag began during the summer when the Portugal international appeared to be trying to force a move away from United. In October, Ronaldo refused to appear as a late substitute in a win over Tottenham Hotspur and left the bench before the end of the game. Ten Hag took the decision to suspend him from first-team training and make him unavailable for their 1-1 draw with Chelsea.
Some sources close to the club believe Ronaldo's interview was designed as a "power play" to force a move away from Old Trafford in January while also negotiating a financial settlement for the remaining months of his contract, which runs until June.
United have been open to letting Ronaldo leave for free since the summer but have been reluctant to agree to a payoff.
Ronaldo is set to begin play with Portugal in Group H at the World Cup in Qatar against Ghana on Nov. 24, followed by matches with Uruguay and South Korea.
ESPN writer Rob Dawson contributed to this story.