Blatter also warned money in football added to the pressure on referees
Fifa president Sepp Blatter believes making referees fully professional would improve the standard of officiating in big matches.
Blatter spoke out in the wake of Chelsea's controversial departure from the Champions League semi-finals.
"I will repeat it, and I have been saying it for 10 years at least, we must improve refereeing," he said.
"It's time to have professionals. We should only use professional referees in high-level competitions."
Blatter was on a plane during Wednesday's match between the Blues and Barcelona and has yet to see the whole game, but he insists that full-time referees are necessary for the long-term good of the elite game.
"We have professional referees in England, we have professional referees in all sports in France. We have this kind of professionalism in Italy during the season, they are under contract," he added.
"We have had professional referees in Mexico, in Brazil and in Argentina and I think this is one of the most important things that refereeing is their profession, this is their job.
"There will always be questions if the referee is good or not good but I will say the future of our game is in the hands of the man with the whistle because there is so much at stake, such as in this match."
Meanwhile, Fulham manager Roy Hodgson has hit out at TV pundit Jamie Redknapp's criticism of the choice of Tom Henning Ovrebo as referee for the Stamford Bridge clash.
Redknapp questioned the decision to allow the Norwegian, who combines officiating with his work as a psychologist, to oversee such a high-profile match.
Ovrebo was criticised on and off the pitch
Barcelona scored in injury time to earn an aggregate victory, but controversy surrounded the performance of Ovrebo who turned down four Chelsea penalty appeals during the match.
But Hodgson said: "Do you want to go down the Redknapp route - only England, Italy and Spain count?"
"There's 60 countries in Europe. Do we say to the other 57: 'Sorry pal, you're not Premier League'."
Hodgson, who managed Viking FK in Norway in 2004-5, added: "Norway is good enough. The average crowd in Norway is 15,000 and that's in a country of 4m. We can only average 25,000 in a country of 60m people.
"What are we going to do in future? Are we going to make certain because the Premier League has Sky Sports behind them and loads and loads of money if you are not in England then forget all about it?
"Are we going to say 'You're from Spain, you might be just about okay but the rest of you, Switzerland, France, Poland, Russia, Austria, Ukraine, Slovenia, Serbia, you don't count?' It's nonsense."
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