BERN (REUTERS) - Nearly one-third of matches in this season's Champions League have been one-sided, ending in a difference of three goals or more, according to a survey by a Swiss-based institute.

The CIES Football Observatory analysed results in 29 European competitions - 27 domestic leagues plus the Champions League and Europa League - and found that the number of "very uneven" games had increased in 20 of those compared to last season.

"This analysis reveals the general trend towards competitive imbalance in European football," it said.

Uefa president Aleksander Ceferin has said that lack of competitive balance was the biggest issue facing European club football.

The flagship Champions League has become increasingly dominated by a handful of elite clubs while many domestic leagues have turned into one-horse races, such as the German Bundesliga, where Bayern Munich are cruising towards a sixth successive title.

The CIES study said the Champions League had the highest number of games ending in a difference of three goals or more at 29.5 per cent, compared to 21 percent at the same stage last season.

Of Europe's five biggest domestic leagues, the figure was highest in the English Premier League at 21.9 per cent and was lowest in the Bundesliga at 11.1 per cent, down 5.6 per cent on last season despite a number of high-scoring games involving runaway leaders Bayern.

The figures for the other big five leagues were 19.8 per cent in Italy's Serie A, 17.9 per cent in Spain's La Liga and 17.6 in France's Ligue 1.

A relatively small percentage of Europa League games, 16.1 per cent, was uneven while the Russian league had the least number of unbalanced matches at 10.5 per cent, the report said.