Israeli police say they have arrested dozens of members of an extremist soccer fans' group.

Police spokeswoman Luba Samri said on Tuesday that 56 suspected members of the "La Familia" group of Beitar Jerusalem fans were arrested in an overnight raid.

She says stun grenades, firecrackers and other banned pyrotechnics were confiscated. An undercover agent who had infiltrated the group over the past six months led to the breakthrough.

Beitar has long tried to contain the tightly knit fan group whose behavior has had the team docked points and forced it to play before empty stadiums.

The group is routinely abusive toward opposing players, taunting them with racist and anti-Arab chants. Beitar has asked police to help rein in the group, which is also suspected of attacking team facilities.