Sir Alex Ferguson has claimed Swansea captain Ashley Williams could have killed Robin van Persie when he struck the ball at the Dutchman's head during the teams' 1-1 draw at the Liberty Stadium.
Van Persie reacted angrily when Williams fired the ball at him from close range - apparently to make a clearance although the whistle had already gone for a foul in United's favour - leading referee Michael Oliver to show yellow cards to both players.
Ferguson, though, told Sky Sports after the game that he believed Williams' actions had been "absolutely deliberate" and that they were extremely dangerous.
"The whistle has gone, the game is stopped and he's done that right in front of the referee," the United boss said. "He could have really killed the lad. It's a disgraceful act. He should be banned for a long, long time."
Football Association rules mean no retrospective action can be taken against Williams due to the fact the referee saw and dealt with the incident at the time, but Ferguson said: "He could have been killed - the referee has got to look into it.
"Irrespective of him having a yellow card, he ought to be banned for a long time because that's the most dangerous thing I've seen on a football field for many, many years."
Williams had looked to downplay the incident in his own post-match interview with Sky Sports.
"I tried to clear the ball. It hit him on the head,'' he said. "I was trying to clear the ball. He was obviously a bit angry about that. It was a much ado about nothing."
Swansea boss Michael Laudrup was surprised when informed of Ferguson's remarks.
He said: "I did not see it at the time as there were a lot of players involved, but I saw it afterwards. I don't think he (Ferguson) meant literally killing him.
"Things happen in a game and I am sure Ashley and Van Persie shook hands at the final whistle and we move on. When your pulse is on 180 then you can say things during the game you don't mean but then afterwards it is back to normal."
Information from the Press Association was used in this report