Gordon Brown warned the Afghan government today that he will not continue to risk the lives of British troops to defend a corrupt regime. In a clear policy shift, the Prime Minister cautioned President Karzai that unless he quashes endemic corruption he will have “forfeited” his right to international support. As he tried to shore up faltering public opinion at home by claiming that the conflict was a “necessity, not choice”, Mr Brown appeared to open the way for a possible exit strategy. “I am not prepared to put the lives of British men and women in harm’s way for a government that does not stand up against corruption,” he said.