Europe's top-division clubs generated a combined profit for the second successive year in 2018, but the gap between the wealthiest sides and the rest continues to grow, according to a new report published by UEFA.

The annual "benchmarking" report from European football's governing body calculates that the combined profit of the 700 top-tier clubs across the continent was 140 million euros ($156 million) with total revenues up to 21 billion euros, an increase of one billion euros.

However, 75 percent of all revenues were generated by the so-called "Big Five" leagues of England, Spain, Italy, Germany and France. In addition, more than half of all top-division revenues for 2019 will be generated by just the top 30 clubs, according to preliminary reporting for the year.

That underlines the power wielded by the continent's very biggest sides, notably England's so-called "Big Six" and the likes of Real Madrid, Barcelona, Juventus, Bayern Munich and Paris Saint-Germain.

However, UEFA also highlight concerns about growing polarisation, both between the biggest leagues and the rest and between leading clubs in smaller leagues and those below them.

"Despite a general improvement over time, TV distributions within many leagues are heavily skewed in favour of the biggest/most successful clubs, thereby widening the revenue gap between the big clubs and the others," the report says.

UEFA president Aleksander Ceferin said in the foreword to the report: "The report highlights a number of threats to continued European football stability and success.

"These include the risks of globalisation-fuelled revenue polarisation, of a fragmenting media landscape, and of cases of over-dependence on transfer activity revenue."

UEFA president Aleksander Ceferin admits that a new report "highlights a number of threats" to European football
UEFA president Aleksander Ceferin admits that a new report "highlights a number of threats" to European football AFP / Fabrice COFFRINI

The latest Deloitte Football Money League, published this week, ranked Barcelona the top club for 2018/19, ahead of Madrid, becoming the first to break the 800 million-euro barrier in revenue.

However, Deloitte's report also showed that the Spanish champions generate almost six times the revenue of the fifth-biggest earning La Liga club, thanks to the success of their commercial operations.

Even within the "Big Five" leagues, the Premier League is far ahead of the rest -- it's combined revenue of 5.4 billion euros in 2018 compares with 3.2 billion euros in the second-ranked German Bundesliga.

France's Ligue 1 is fifth with 1.7 billion euros of combined revenue in 2018, but champions PSG's income alone reached almost a third of that figure.

The report comes following a year in which radical changes to the format of the UEFA Champions League have been proposed by the European Club Association, and less than two months after Real president Florentino Perez became president of the new World Club Football Association.

It has been reported that the WCFA has held talks with private equity partners over the formation of a global league.

However, Ceferin added: "The report also shows that European club football is strong, united and resilient, and I am certain that European football can and will overcome these challenges and others just as successfully as it dealt with the threat of spiralling losses in the recent past."

The increased profits contrast with 2011, before UEFA's introduction of the current Financial Fair Play system, when clubs reported an overall loss of 1.7 billion euros.