Undercover policing operations should have to be authorised in advance by a judge, an ex-PSNI Chief Constable has said.
Sir Hugh Orde, now president of the Association of Chief Police Officers, said the change was needed to restore public confidence.
It follows concerns about the role played by ex-Metropolitan Police constable Mark Kennedy, who spent seven years posing as an environmental activist.
Six protesters accused of planning to invade a power station claimed prosecutors dropped charges against them after Mr Kennedy offered to give evidence on their behalf.
Sir Hugh said the benefits of judicial oversight of future operations would “far outweigh the additional administrative burden”.
Sir Hugh said: “The current system of retrospective inspection is, in my judgment, no longer sufficient to secure the confidence of right-thinking people that such interference with citizens' rights (with its foreseeable collateral intrusion on many) is appropriate.”