The governing body of European soccer announced on Tuesday an investigation into allegations of anti-Semitic behavior from fans of a local German team towards supporters of an Israeli club during last Thursday's match in Berlin.
The Union of European Football Associations (UEFA) announcement came almost a week after Maccabi Haifa fans claimed they were insulted and threatened by some Union Berlin supporters at the Europa League Conference game, which took place at the Nazi-era-built Olympic Stadium.
UEFA has appointed an Ethics and Disciplinary Inspector to "conduct a disciplinary investigation regarding potential discriminatory incidents."
Allegations include anti-Semitic insults, beer thrown at Haifa supporters, and one suspect accused of incitement for repeatedly shouting "Sieg Heil." An Israeli fan told German newspaper Die Welt that a Union Berlin supporter tried to set fire to a small paper Israeli flag, which police later confirmed.
Dirk Zingler, president of the Union Berlin club, later apologized by branding their supporters' behavior as "shameful and intolerable."
"We apologize to those affected," added Zingler. "We will never tolerate discrimination in our ranks. It is important to remain vigilant and to work tirelessly against it."
The recent anti-Semitic allegations come in light of increased hate crimes committed towards the Jewish population.
Berlin's Olympic Stadium was built for the 1936 Olympics hosted by Nazi Germany, where one of the most controversial sports events in history took place.
Thursday's match was switched from Union's Alten Foersteriei ground to the Olympic Stadium to meet UEFA requirements.