Manchester United are falling behind Barcelona and Real Madrid in the 'Money League' of the world's richest clubs, according to a new report.

Real Madrid: Top of the 'Money League'

The report by analysts Deloitte says although United's revenues continue to grow they have not kept pace with the Spanish giants, who have the advantage of being able to negotiate their individual TV rights deals.

United's failure to qualify from the group stage of the Champions League this season will see the gap widen further next year, say Deloitte.

Real Madrid remain top of the money league with revenues in 2010/11 of 479 million euros (£438m) with Barcelona second on 451m euros (£398m) and Manchester United third on 367m euros (#349m).

The report states: "We are starting to see widening gaps between clubs at the top of the Money League.

"Manchester United's consistent on-pitch success has helped establish it as a continued fixture in the top three of the Money League, yet in recent years a gap has grown between themselves and the Spanish giants Real Madrid and Barcelona, rising again to 83.7m euro in this year's edition.

"United's failure to qualify for the 2011/12 Champions League knockout phase will have a detrimental effect on revenues relative to the top two, which may result in this gap increasing to over 100m euro.

"In addition, there is a 70m euro gap between fourth-placed Bayern Munich and fifth-placed Arsenal.''

Chelsea remain sixth in the Money League, but Liverpool have fallen a place to ninth behind Inter Milan and the report states the Reds' lack of European football could see them drop out of the top 10 unless they at least qualify for the Europa League.

"The club needs European football each year to maintain its status in the Money League top 10 in future editions,'' says the report.

"In the medium to longer term, the Warrior Sports kit deal will underpin further commercial revenue growth, whilst formulating a viable plan to either redevelop Anfield or move to a new home is key in driving matchday revenue increases."

Tottenham are 11th in the Money League, just in front of Manchester City thanks to last season's Champions League income, but the value of the huge Etihad sponsorship deal, which could total £400m, should see City break into the top 10 next year.

Alan Switzer, a director of Deloitte's sports business group, said: "The club's heavy squad investment secured Champions League football for 2011/12. When combined with the groundbreaking 10-year partnership with Etihad, this will provide substantial growth across all three revenue sources and will see City break into the top 10 in the Money League next year."