Bundesliga giant Bayern Munich was the only champion in eight major European football leagues to post a profit in the coronavirus-hit 2020-21 season, a study by the auditing firm KPMG showed Wednesday.

The German champion just scraped into the black with an after-tax profit of 1.8 million euros ($2.0 million), also recording the lowest ratio of staff costs to operating revenue at 58%.

"While the reopening of stadia and some major commercial deals signed recently may provide some optimism ... the pandemic only magnified the financial sustainability issues and fragility of the football ecosystem," KPMG's global head of sports, Andrea Sartori, said.

Exemplifying those problems, Serie A winner Inter Milan posted an annual loss of 245.6 million euros on operating revenues of 347.5 million, with La Liga champion Atletico Madrid losing 111.7 million euros on revenues of 349.6 million.

Topping the revenue table was Premier League champion Manchester City, generating 644.2 million euros, a rise of 17% from the previous season, the study showed.

City, who reached the final of the Champions League, also leapfrogged local rival Manchester United (557 million euros) for the first time.

Bayern was second behind City with revenues of 597.5 million euros, while Turkish Süper Lig winner Beşiktaş had the lowest revenue among the eight champion clubs at just 59 million euros.

Six of the clubs increased broadcasting revenues, benefiting from deferred income related to matches postponed from the 2019-20 season and played after June 2020.