An Amnesty International report has accused the French authorities of allowing police to abuse Arab and African suspects with impunity.
Amnesty says French police at times ignore their own guidelines
The human rights group said officers had used "excessive and sometimes lethal force against suspects without fear of serious repercussions".
The report said complaints about police conduct rose by nearly 20% in 2004.
It highlighted two cases where Arabs were killed by police. Both took 10 years to come to court.
The report, entitled France: The Search for Justice, examined cases of police abuses over the past 10 years.
Amnesty complained of "a 'two-speed justice' system, which prosecutes cases brought by police officers far more quickly than those brought by their victims".
The French government is preparing its response.
Amnesty's UK director Kate Allen said there was "a clear need for an independent mechanism to investigate allegations of abuses by the French police".
Amnesty said there was a lack of safeguards for detainees, a lack of respect for internal French police guidelines, and that the French penal code "contains no full definition of 'torture'".