Borussia Dortmund and Liverpool have both been charged by UEFA for offences committed by fans during their Europa League quarter-final first leg on Thursday.
UEFA has confirmed disciplinary proceedings have been opened against both clubs.
Borussia Dortmund have been charged with stairways being blocked, while Liverpool face a charge in relation to their supporters letting off fireworks at Signal Iduna Park.
The cases will be dealt with by UEFA’s control, ethics and disciplinary body on May 19.