A total of 39 arrests have been made and four police officers injured following violence outside Villa Park before Aston Villa's Europa Conference League tie with Legia Warsaw on Thursday, West Midlands Police told ESPN.
Police were hit with missiles from fans, videos posted to social media showed. West Midlands Police told ESPN that one officer was taken to hospital, while two police horses and two police dogs were also injured.
Legia Warsaw said Aston Villa had given the Polish club a lower allocation of tickets than they were entitled to under UEFA regulations.
Police denied entry to travelling fans after the unrest occurred, leaving the away stand empty. Aston Villa won the match 2-1.
Four police officers were injured in the pre-match violence. James Baylis - AMA/Getty Images
"Instead of defusing potential pre-match tensions, Aston Villa F.C.'s restrictive measures as the host club unnecessarily exacerbate the atmosphere. In our view, such measures are counterproductive and unwarranted," Legia Warsaw said in a translated statement.
ESPN have approached Aston Villa for comment.
The Mayor of West Midlands, Andy Street, said he hopes UEFA "will now move swiftly to take strong action."
UEFA told ESPN in a statement on Friday: "UEFA strongly condemns the unacceptable violence which occurred around the Aston Villa v Legia Warsaw match.
"UEFA is in the process of gathering all official reports from the game before deciding on potential next steps."
Information from Reuters contributed to this report.
Source: espn.co.uk