Bulgarian police arrested 14 football fans on Tuesday in connection with crowd violence at two domestic league matches before the winter mid-season break.
Detectives had spent recent weeks examining evidence, including pictures and video footage of the trouble, police said in a statement.
Twelve fans, including a 31-year-old woman, were arrested for violent disorder during CSKA Sofia's 1-0 win over bitter city rivals Levski on October 28.
The 'eternal derbies', as matches between the two most popular clubs in the Balkan country are known, have a history of crowd trouble with police unveiling strict security measures ahead of every game in recent years.
Two men were detained for using fireworks and pelting players with broken seats during CSKA's 2-2 draw against surprise leaders Ludogorets in the last game before the winter break on November 28.
Sofia police said further arrests were planned.comments