SIR Alex Ferguson today demanded FA chiefs ban Swansea's Ashley Williams after claiming the defender could have killed Robin van Persie during yesterday's 1-1 draw at the Liberty Stadium.

Ferguson was left livid after Williams lashed the ball against the back of van Persie's head as the Dutchman lay on the ground.

The striker then appeared to move his head towards Williams' face in the melee that followed.

Both players were booked by referee Michael Oliver.

Ferguson accused the Welsh centre-half of deliberately trying to hurt van Persie, and said his player could have suffered a broken neck.

"You can clearly see that he could have been killed," said a furious Ferguson.

"The FA has got to look into it regardless of the fact that he has been given a yellow card.

"He should be banned for a long time because that was the most dangerous thing I've seen on a football field for many years.

"It was absolutely deliberate. The whistle has gone, the game has stopped and he has done that right in front of the referee.

"He could have broken his neck. It was a disgraceful act by the player, he should be banned for a long time. Robin van Persie is lucky to be alive."

Swansea manager Michael Laudrup appeared bemused when informed of Ferguson's controversial comments.

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 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 afterwards it's back to normal."

Williams insisted he had not acted maliciously. The Wales captain defended his conduct and said: "I tried to clear the ball and it hit him on the head.

"I was trying to clear the ball. He was obviously a bit angry about that. It was a much ado about nothing."

The controversy overshadowed an entertaining encounter as United missed the chance to move six points clear at the top of the table.

Patrice Evra put the visitors in front by heading home a van Persie corner in the 16th minute, but Michu tapped in his 13th league goal of the season after David De Gea had parried Jonathan De Guzman's shot.

Ferguson refused to criticise his players, despite their failure to find a winner during a final half hour where they put Swansea under incessant pressure.

He said: "We absolutely battered them. It was a great performance in the second half. It is unbelievable we didn't win the match. My only criticism is that the final ball at times let us down. No criticism of the performance, it was very good."

The result means United's lead over Manchester City now stands at four points in the Barclays Premier League.