Nobody is allowed to discriminate against another person due to their race, and the police are certainly not above the law when it comes to racial discrimination. If they do discriminate against you because of your race you are well within your rights to make a claim against them thanks to the Race Relations Act 1976.
This is a very complex document that can’t be broken down into a few hundred words. We advice that you get read ‘Racial Discrimination – Your Legal Rights’, a leaflet courtesy of Community Legal Service Direct which is available online, as is the act itself. If you after reading these you feel you have a case against the police for racial discrimination then find a solicitor experienced in this type of case.