British forces killed seven gunmen and destroyed the headquarters of the serious crimes unit in southern Basra on Monday (December 25) after learning prisoners there were about to be executed, the British military said. British and Iraqi forces had seized one of the main police stations, saying the Major Crimes Unit had become a "criminal enterprise". "British forces raided the headquarters of the Major Crimes Unit of the Basra Police and the Interior Ministry. They destroyed the building and released detainees who are accused of terrorist operations," said the policeman, who declined to give his name. British military spokesman Captain Tane Dunlop said the building was demolished with explosives after the pre-dawn assault by around 1,000 troops. An armoured British force of Challenger tanks and Warrior armoured fighting vehicles came under rocket-propelled grenade and machine-gun fire from alleyways as it approached the station, said Major Charlie Burbridge, another British spokesman. The force returned fire with heavy machine-guns, killing seven gunmen, Burbridge said. The unit has long been accused of involvement in murders, attacks on coalition forces and kidnappings. The British military had planned to disband the unit but decided to act on Monday after learning on Sunday (December 24) that some of the prisoners, all suspected criminals, inside the police station faced imminent execution, Burbridge said. "Regrettably, the multi-national forces have insisted to get involved in massive troops, which we do not actually need in such an operation, and entered the building where there were prisoners and consequently reduced the building to rubble," Ali Ibrahim, Head of Basra Security Committee said. "More than 60 prisoners were moved from this place to another place," Mohammed al-Askari, a defence ministry spokesman said. The police station, one of the biggest in Basra, was where two plain-clothes British soldiers were briefly held in September 2005 before being freed in a raid by their comrades. Police forces in Iraq's southern city of Basra said on Monday (December 25) they would have no dealings with the British forces who earlier stormed and destroyed the headquarters of the serious crimes unit in the city.