The match was stopped and the players left the pitch for several minutes during the second half of the clash following ugly scenes in the stands where flares were thrown in the direction of the home fans.

Five people, believed to be Barca fans, were detained by police and an investigation has been launched following the trouble.

Barca, who won the match 2-1 thanks to two late goals, have responded to the disturbances by releasing a lengthy statement on Sunday emphasising their stance of "zero tolerance" against such incidents.

"The outbreak of violence in a football stadium, in this case involving fans that use Barca symbols but that in no way represent the supporters of FC Barcelona, is once again of concern to all people in football, and all clubs and all those who form part of them," part of the statement read.

"In recent years, Barca have shown that they are inflexible, that they have acted with conviction and forcefulness, and have left no room for misunderstood comprehension of uncivil behaviour, in order for stadia to be cleaned of this violence.

"Yesterday's incidents showed that the right thing is being done. It is once again time for zero tolerance, whatever happens, and whatever the cost."

Barca president Joan Laporta also distanced his club from the troublemakers, saying: "People shouted at me as if I was responsible for what was happening.

"I can only tell them we take absolutely no responsibility and that Barca have spent six years taking measures in order to stop these kinds of incidents from happening in the stadium."