Belgian Pro League side Beerschot said they will identify and sanction the fans who threw flares onto the pitch during Sunday's match at local rivals Antwerp, leading to the match being abandoned.
The visiting fans threw the flares when Beerschot were trailing 4-0 in the derby, 75 minutes into the match. Hosts Antwerp were awarded a 5-0 win after Beerschot forfeited the rest of the game.
It was bottom side Beerschot's eighth loss in a row, leaving them with only one point after nine matches.
"We understand the frustration of our supporters and we too are extremely frustrated. However, the club strongly condemns the behaviour of these few and Beerschot will identify and sanction the supporters involved," the club said in a statement.
Local media reported that some spectators clashed with police after the match, with the authorities using water cannons to disperse the crowd outside the stadium.