Algerian police are under investigation following social media images of officers apparently attacking football fans after a first division match on Tuesday, according to official sources.Trouble flared after a section of fans of Mouloudia Club d'Alger (MCA) reacted angrily to their team's 1-0 home defeat to USM Bel Abbes (USMBA).The MCA fans tore up plastic seats in the stands and threw them on to the field and at police. A total of 40 people, including 18 police officers, were injured.Video footage, however, has turned the spotlight on the police as it appears to show plain clothes officers, armed with batons, throwing broken seats back at the fans.The video also shows a young supporter on the ground being brutally beaten with batons by a group of men who appear to be police officers.In a statement the national police force (DGSN) said it was opening an inquest into the authenticity of the video showing "inappropriate behaviour by certain officers in exercising their duties".* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and FacebookAccording to the statement, 42 fans were arrested for "disturbances of public order, carrying knives or possession of drugs".Last month 80 people were injured during violence after another match involving MCA. Algerian football has been plagued by almost daily violence for some years.In 2014 Albert Ebosse, a Cameroon striker with Algeria's JS Kabylie, was killed on the field by a projectile thrown from the stands. But neither the shock triggered by the tragedy, nor sanctions or fair-play campaigns have succeeded in quelling the phenomenon. Last December, clashes between rival fans at an amateur derby in eastern Algeria left one person dead. In mid-April, more than 100 people were injured in clashes at an Algerian Cup semi-final, pushing the interior ministry to set up a commission of inquiry, determined to "put an end" to the violence.