Sir Alex Ferguson and Carlos Queiroz have been found not guilty of improper conduct after the FA Cup quarter-final defeat to Portsmouth.

Ferguson had said the performance of Martin Atkinson, the referee, during his side's 1-0 loss was "unacceptable". He also accused Keith Hackett, the head of the Professional Game Match Officials Board, of "not doing his job properly".

Ferguson and Queiroz, who also criticised Atkinson, were unhappy United were not given a first-half penalty for a challenge on Cristiano Ronaldo. Speaking after the match, Ferguson said: "It's absolutely ridiculous. I cannot explain it. Managers get sacked because of things like that and he's going to referee a game next week."

He added: "He (Hackett) is not doing his job properly and he needs to be assessed. I'm assessed as a manager, players are assessed, referees should be assessed properly by the right people. That performance today should not be accepted by our game."