Manchester United manager Sir Alex Ferguson says the decision to give Newcastle a penalty in his side's 1-1 draw at Old Trafford was a "travesty".
Referee Mike Jones gave the spot-kick after after assistant John Flynn flagged following Rio Ferdinand's tackle on Hatem Ben Arfa.
Ferguson said: "The referee thought it was a corner and he was nearer to the incident. It was an absolute travesty.
"The problem is that assistants are not full-time even if the referees are."
He added: "I don't think anyone in the ground thought it was a penalty apart from the assistant referee."
Ferguson supported his argument by referring to an incident in the recent home game against Sunderland when a linesman flagged for a penalty, only for referee Lee Mason to correctly give the decision in United's favour.
He said: "[In the Sunderland match] The linesman gave a penalty for a handball, which was obviously an opponent's hand.
"The referee was put in a terrible quandary, but he knew full well it was a handball from an opponent and overruled the linesman. That is what he should have done against Newcastle."
Javier Hernandez had given United a 49th-minute lead before Demba Ba's penalty pulled Newcastle level after referee Jones ruled Ferdinand had brought down Ben Arfa.
Manchester United striker Michael Owen, who is injured, tweeted: "The less said about the penalty decision the better. Unbelievable. Video technology just for goals or major decisions too?
"It took more time for the ref and linesman to come to that decision than it would for somebody to watch a replay and they still got it wrong."
It is understood Jones conferred with Flynn because the referee was not 100% sure whether it was a penalty or not.
In a statement to BBC Sport, the Premier League and Professional Game Match Officials said: "Our assistant referees are part-time and to date there has been no call from the clubs to make them full-time.
"Select group assistant referees do have high standards of training and performance monitoring.
"Over the course of the season the standard of their decision making is of an exceptional high standard."
The draw leaves United four points behind leaders and rivals Manchester City, who play Liverpool at Anfield on Sunday, but asked whether the champions' rivals were getting too far ahead of his side, Ferguson quipped: "It would be - in April."
Newcastle manager Alan Pardew accepted his team had "got a break", although he did feel Ferdinand had taken a chance by sliding in.
"I thought the tackle was risky. He definitely played the ball. I have seen it," said Pardew.
"If it was against me I would be very aggrieved. We got a break but we still had to score the goal and Demba was very cool."
The draw leaves Newcastle in fourth place, and Pardew praised his side's resilience.
"Our attitude and defending deserved a point. The heroism in that penalty box was unbelievable. They were Geordie heroes," he said
