Spanish clubs Real Madrid and Barcelona maintain the top two slots in Deloitte's Football Money League, followed by Manchester United, Bayern Munich, Arsenal and Chelsea, the report said, based on revenue for the 2010/11 season.
"Continued growth of the top 20 clubs during 2010/11 emphasises the strength of football's top clubs, especially in these tough economic times," said Dan Jones, partner in the Sports Business Group at Deloitte.
"Whilst revenue growth has slowed from eight percent in 2009/10 to three percent in 2010/11, their large and loyal supporter bases, ability to drive strong broadcast audiences and continuing attraction to corporate partners has made them relatively resilient to the economic downturn," he added.
"In much the same way as the Premier League is for England, they are very successful exports for the Spanish economy," Jones told Reuters.
"The challenge for Spain is that these two are so far ahead of the rest on and off the pitch."
The top 20 - who make up the world's highest earning clubs - are drawn from the big five European leagues. Six are from England, five from Italy, four from Germany, three from Spain and two from France.
Revenue at Real Madrid was 479.5 million euros, against 450.7 million for Barcelona and 367 million for Manchester United, beaten by Barcelona in last season's Champions League final.
However, new rules introduced by European football's governing body UEFA mean clubs must curb their losses or risk exclusion from major tournaments.
"Football clubs have been very successful over the past 20 years at generating more revenue but less good historically at cost control and that is what Financial Fair Play is
