William Gaillard admits it is difficult for Uefa to ensure there is a pan-European security policy for games.
"If you go to the football supporters' organisation's website, you will see it's quite interesting the testimony of the Liverpool fans who were in Athens and many experienced problems," Gaillard told Sky Sports News.
"They said there is a small group of people that, and they put it this way, make it a badge of honour to get into stadiums without paying.
"That's also a case in some English stadiums and supporters themselves are saying that.
"The problem, I think, is very much a marginal one in England, but away we have problems.
"For example, there was some racism this year, we've had problems also of organised groups of supporters, mostly in Southern Europe, who belong to extremist political factions who want confrontations with police or stewards.
"We have drinking problems, which is more prevalent in Northern Europe. All these factors make it difficult to have a pan-European policy, but this is what we are working on."
