European football's governing body have opened an investigation that will examine several videos of fans singing in and around the Nou Camp stadium on March 4.
"We have received some footage showing Celtic supporters singing some alleged anti-Queen and pro-IRA songs - sectarian songs," a Uefa spokesman said. "Basically we take care of all manifestations of sectarian singing. The only condition is that it must be in the immediate surrounding area of the stadium.
"There was alleged sectarian singing inside the stadium. If the investigation is conclusive, then a disciplinary case would be opened. It will depend on the easiness of having these songs understood and the quest of finding other evidence."