Paris - French President Francois Hollande has called for "justice" over the alleged rape of a black youth with a police baton, an incident that has sparked 10 nights of rioting and more than 200 arrests."Justice must be served," Hollande said during a visit to Aubervilliers, located in the tough Seine-Saint-Denis region northeast of Paris where a 22-year-old youth worker, identified only as Theo, was assaulted on February 2.But Hollande also condemned the ensuing riots, which have shaken the belt of gritty suburbs surrounding Paris.The injuries sustained by Theo during a stop-and-search operation in the suburb of Aulnay-sous-Bois have sparked clashes with police and arson attacks across the impoverished, ethnically-mixed housing estates that ring the French capital.The interior ministry said 245 people had been arrested over the protests which began on February 4. Several dozen have been taken into custody.Police brutality Theo suffered severe anal injuries requiring hospital treatment during his arrest by four officers, one of whom allegedly sodomised him with a truncheon.One officer has been charged with rape and the three others with assault. All four have been suspended from the force.On Tuesday, a separate investigation was launched into claims that one of the four officers beat up another black youth in Aulnay-sous-Bois on January 26.The youth, also aged 22 who gave his name as Mohamed K, told L'Obs news weekly that he had been punched, kicked and beaten with a baton. Pictures published by the paper showed severe swelling and bruises to his face.Hollande said France was determined to "show that we are capable of living together in a peaceful society, but where respect is the rule and where we must be firm towards those who diverge from this principle".Separately, leading French artists launched an appeal calling for far-reaching reforms of the police to prevent similar episodes of alleged brutality.The call, published in Wednesday's edition of the leftwing daily Liberation, urged the use of cameras on police uniforms, the reintroduction of neighbourhood policing and an overhaul of training policy.The nationally-known signatories included movie director Nils Tavernier, singer Patrick Bruel, actresses Josiane Balasko and Mathilda May, and Olivier Py, director of the Avignon arts festival.'Fuel to the fire'With presidential elections in April and May, the alleged assault, which follows the death of a young black man in police custody in another Paris suburb last year, has become a campaign issue.Far-right leader Marine Le Pen on Monday launched a petition "to support the police" after blaming "laxism in French society" for the problems of the restive suburbs.The head of the anti-immigration National Front party called for a "major tightening of the screws" to boost police capabilities.Socialist presidential candidate Benoit Hamon lashed Le Pen, saying she was "adding fuel to the fire". "She encourages violence through her hateful rhetoric," Hamon said.On Monday, Interior Minister Bruno Le Roux made an appeal for "responsibility, calm (and) faith in the justice system".Hollande, who visited Theo in hospital last week, decided not to seek re-election.The leftist Hamon, who won the Socialist nomination, is given little chance of getting past the first round on April 23.The latest voter surveys show Le Pen with 27% support for the first round -- more than any other candidate - although she is currently not expected to triumph in the May 7 runoff vote.