A formal counter-terrorist "supergrass" scheme should be initiated and "more acceptable" criminal offences introduced to replace control orders, according to the government's terrorism law watchdog.

Lord Carlile of Berriew QC, who was appointed by the then home secretary David Blunkett as independent reviewer of the operation of the counter-terror laws, also said yesterday that the number of stop and search incidents under the terrorism legislation could be cut by at least 50% without increasing the risk to the public.