The Hacked Off campaign, which represents many victims of newspaper intrusion, said Lord Justice Leveson had given the Prime Minister a "workable, proportionate, reasonable solution" to the problems of press abuse.
But the group added that David Cameron "had not done his job" by failing to accept the full recommendations of the report and was wrong to trust Editors to "behave themselves".
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Rain will spread eastwards across southern areas tonight. Clear and frosty in the north.
Political leaders will go head-to-head at ITV's studios in MediaCityUK in Salford, ITV has confirmed, as the set for the event is unveiled.
More than 100 people claiming to represent working people across Britain have signed a letter backing Labour in the general election.