Spanish police have said eight Leicester City fans were arrested for “causing a mess” ahead of their Champions League tie against Atletico Madrid.
The fans remain in custody following clashes with police on Tuesday evening and will appear in court on Thursday.
Police said six officers were also attacked in the disturbances.
BBC journalist Phil Mackie said he witnessed what appeared to be an unprovoked attack from officers.
He said he met supporters who had been left bruised after being hit on the head, arms and knees.
A spokesman for Leicester City said: “We have received reports from local police of a small number of arrests following minor incidents in Madrid on Tuesday evening.
“We have provided extensive advice for travelling supporters ahead of every away fixture in the competition and we would urge our fans to adhere to the guidance issued.”