Police intervene amid chaos at Brandywell Stadium in Derry City

European football’s governing body UEFA said it was investigating the role of both clubs during the stadium event.

It said the allegations against CSKA Sofia included damage to the stadium, throwing objects, racist and/or discriminatory behaviour, crowd disturbances and breaches of decency.

Allegations against Derry City included dominant assaults on the playing field, throwing objects, crowd disturbances and inadequate protection of playing areas against trespassers.

In a statement, Derry City Football Club said they “unequivocally condemn the violence witnessed at tonight’s match”.

“The club is working closely with UEFA, PSNI, CSKA Sofia and our security partners to establish full information surrounding the incident,” it added.

The BBC has contacted CSKA Sofia for comment.