UEFA has opened disciplinary proceedings against Bayern Munich after a banner relating to Kosovo was displayed during Tuesday's Champions League match with Arsenal.
The soccer body said it was also considering action, after a report from Football Against Racism in Europe, over another banner directed at the English Premier League club.
"UEFA opens disciplinary proceedings against Bayern for banner about Kosovo," UEFA press officer Pedro Pinto said on Twitter on Wednesday.
Kosovo, which declared independence from Serbia six years ago, is not a member of FIFA or UEFA but is allowed to play friendlies against other nations provided no national symbols, including flags, are displayed or anthems played.
They played their first match, against Haiti, earlier this month.
Scottish champions Celtic were fined €50,000 in December after "illicit" banners were displayed by fans during a Champions League group match against AC Milan.