Riot police in the Polish city of Wroclaw used a water cannon to stop trouble between Chelsea and Real Betis fans before the Uefa Conference League final.
Hundreds of fans clashed in Wroclaw Market Square on Wednesday afternoon – with the Lower Silesian Police saying 28 supporters had been arrested.
Police indicated that number would rise, with arrests of fans involved in the incident “ongoing”.
The final of the the third-tier European competition is at 20:00 BST at Stadion Wroclaw.
Local authorities estimate that more than 70,000 fans have arrived in the city in the south-west of Poland for the final, a number that covers ticket holders and those attending fan zones and other events around the city.
Tens of thousands of fans are expected to pass through the city’s four major fan zones.
“The police very quickly took action to separate the two groups and prevent the escalation of aggressive behaviour,” Lower Silesian Police posted on X after the trouble started after 3pm local time.
“The officers used technical means in the form of a water cannon and direct coercion. According to the findings so far, no-one was injured.”
In a later statement, they said: “At this moment, we can confirm the arrest of 28 participants in the incident. No one will escape legal responsibility and the police will react decisively and appropriately to the situation.”
On Tuesday evening, several clashes between Chelsea and Betis fans took place near Solny Square.
Riot police intervened using tear gas to disperse the crowds. Chairs and glass bottles were thrown as the confrontation lasted for around five minutes.
There were two further clashes in the evening, with minor damage caused by no major injuries reported. Seven fans including, four Spanish supporters, were arrested.
“Zero tolerance for violence on our streets!” Polish Prime Minister Donald Tusk wrote on X, external.
“I thank the police for their decisive actions against the hooligans in Chelsea and Betis shirts in Wroclaw. We warn you: if necessary, the police will be even more ruthless!”
