They want success and they want it to be immediate... that is why they pay these incredible fees

Kingston University's Tom Cannon

It paid $64.5m for the French player Zinedine Zidane, capping an extraordinary few months in which the price of footballers has reached astronomical proportions.

Many observers have likened the boom to the dot.com frenzy in which high tech companies were able to raise billions of dollars on the stock market with dreams rather than solid business plans.

Boom or bust?

The question is whether or not the spending binge is sustainable.

Real Madrid describes the club's finances as being "in a state of economic intensive care" and has had to sell some of its sports facilities to pay for its new player Zidane.

Sir Alex Ferguson argues that these players are scarce assets

"If you look at the clubs, although revenues are going up, their expenditure on players and players wages is growing faster than their income and that is a bubble," Tom Cannon, professor of business administration at Kingston University in London, said.

He added: "It will take a significant club, a club that has been relegated, to not be able to meets its calls on expenditure and its debts and its banks will get impatient.

"If you have one club go down, there will be a knock on effect and more will go down."

Strength to strength?

Not all agree.

"Football keeps financially, in terms of the revenues it brings in, going from strength to strength.

"It is not a dot.com situation, it is not a business that has been set up by 20 or 30 bright people that has no revenues. It is something much more sustainable," argues Dan Jones, a director at Deloitte Touche Sport.

"They have large television contracts in place for the next three years. They have season ticket holders... It is a completely different sort of business model," he added.

A few weeks after Real Madrid's hefty purchase, England's Manchester United weighed in with its own domestic signing record.

It paid �28m for the Argentinean Juan Sebastian Veron after paying �19m on Ruud van Nistelrooy earlier in the spring.

Manager Alex Ferguson justified the bill by saying that these players were scarce assets.

"I have always been maintained there must be one player who can make a difference," Alex Ferguson said.

Does money make a difference?

While the likes of Manchester United and Real Madrid are unlikely to run into serious financial difficulties, very few professional football clubs in Europe are making any profits.

Most of the 92 English clubs are losing money.

I have always maintained there must be one player who can make a difference

Alex Ferguson

Moreover, paying big bucks for top players does not always guarantee success on the pitch.

The current European champion, Germany's Bayern Munich, has shunned headline grabbing transfers and the most it has ever spent on a new player is about �5m.

Prof Cannon said: "In England, Scotland, Spain and Italy, you have this intense commitment to the club, which goes on the border of fanaticism.

"You have fanatical fans who support these clubs to a far greater extent than you see in France, Germany or even in Scandinavia.

"The boards want success, the chairman wants success.. and they want it to be immediate," he added.

"That is why they pay these incredible fees."