Fans of Polish side Legia Warsaw were barred entry to their match at Aston Villa on Thursday following clashes with police outside the stadium in which authorities said three officers were injured.

The unrest occurred ahead of kickoff in the Europa Conference League game at Villa Park, and the police denied entry to travelling fans, leaving the away stand empty.

"We're currently unable to allow away fans into Villa Park following disorder outside the stadium which has seen missiles thrown at officers," Birmingham Police said in a statement.

"Three officers have already been injured and a significant policing operation continues."

Legia Warsaw fans were involved in violent clashes with police outside Villa Park. James Baylis - AMA/Getty Images

Legia Warsaw said Aston Villa had given the Polish club a lower allocation of tickets than they were entitled to under UEFA regulations.

"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.

Aston Villa did not immediately respond to a request for comment.

"No away fans were allowed into Villa Park for this evening's UEFA Europa Conference League fixture with Legia Warsaw on the advice of West Midlands Police following large-scale disorder outside the stadium caused by visiting supporters," the Premier League club said in a statement.

"Approximately an hour before kick-off, Legia fans engaged in planned and systematic violent acts against West Midlands Police officers and a decision was then made by West Midlands Police to exclude all Legia supporters," the statement continued.

"Aston Villa strongly condemns the behaviour of those visiting supporters and would like to thank West Midlands Police for their professionalism in very difficult circumstances."

Reuters contributed to this report.