Chelsea and Manchester City fans have been involved in violent clashes in Porto ahead of this weekend's Champions League final.
Footage shared on social media shows supporters chanting and fighting in the streets and throwing chairs at each other.
Locals were seen attempting to intervene before police eventually broke up the violence. There have been no reports of any arrests.
Thousands of supporters are expected in the city for the match, which was moved from Istanbul to allow English fans to travel within current coronavirus guidance.
Mr Moreira added: "The police were very careful, they know how to handle fans because we are a football city."
Chelsea and City face each other at Estadio do Dragao on Saturday evening in the final of Europe's premier club competition.