LONDON — Liverpool manager Rafa Benitez launched a blistering attack on Manchester United counterpart Alex Ferguson's unpunished abuse of referees and accusations that the league is conspiring against his title defense.

Ferguson "is the only manager in the league that cannot be punished" for criticizing referees, Benitez said on Friday, reading from a prepared statement at Liverpool's training ground.

Benitez complained that the Football Association has been too lenient when dealing with Ferguson's attacks on refs, despite the launch of a high-profile "Respect" campaign aimed at improving behavior toward officials.

While Benitez also voiced his frustration with Liverpool's American owners about the slow progress in negotiations over a new contract, Ferguson was his main target.

The only United reaction came from Bryan Robson, the former captain who serves as the club's global ambassador. He expressed surprise that Benitez delivered the "staged" statement instead of concentrating on Saturday's match at Stoke in the English Premier League.

"Benitez has come out with a rant today which is unbelievable," Robson said on United's TV channel. "I think the boss has got one over on him already."

In May, Ferguson was cleared of improper conduct charges over comments made about referee Martin Atkinson and Keith Hackett, the general manager of Professional Game Match Officials, after United was eliminated from the FA Cup by Portsmouth.

Ferguson said Atkinson's display was "unacceptable" and "on Portsmouth's side."

"He was not punished," Benitez said. "He is the only manager in the league that cannot be punished for these things.

"We had a meeting in Manchester with managers and FA about the 'Respect' campaign and I was very clear: Forget the campaign because Mr. Ferguson was killing the referees, killing Mr. Atkinson, killing Mr. Hackett. But he is not punished. How can you talk about the 'Respect' campaign and criticize the referee every single week? ...

"Every time we go to Old Trafford and the United staff are always going man to man with the referees, especially at halftime when they walk close to the referees and they are talking and talking."

The 67-year-old Ferguson received a two-game touchline ban in November over a confrontation with referee Mike Dean.

The "Respect" initiative was launched after repeated instances of referee abuse last season — notably Liverpool midfielder Javier Mascherano refusing to accept he had been red-carded at United and having to be dragged off the pitch.