Terrorists are plotting more numerous and deadlier attacks against Britain each year, London's police chief warned lawmakers Tuesday. Ian Blair told a committee examining changes to detention laws that his officers face a sharply rising threat from terrorism. "The number of the conspiracies, the number of conspirators within those conspiracies and the magnitude of the ambition - in terms of destruction and loss of life - is mounting, has continued to mount year by year," Blair told the House of Commons Home Affairs committee. Blair told legislators laws must be tightened, allowing police more time to question suspects before they must be charged.