Three police officers were injured outside Villa Park after missiles were thrown at them by Legia Warsaw fans.
The Europa Conference League tie between Aston Villa and Legia began without any away fans inside the stadium, with the travelling supporters contained in a car park behind the Witton Lane stand after clashing with police.
Mail Sport understands that Legia were unhappy with their reduced allocation after Villa reduced their ticket allocation to just 890 based on advice from the police and Safety Advisory Group.
UEFA rules allow the visiting team five per cent of the stadium’s capacity, which would equal 2,100 tickets at Villa Park.