Nick Clegg acknowledged that new powers were needed by the law enforcement agencies to fight crime, but said they must take account of the committee's concerns.
That must be done in a proportionate way that gets the balance between security and liberty right.
Any modernisation of the powers, including possible new legislation, must meet the concerns of the joint committee by having the best possible safeguards and keeping costs under control.
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The Labour leader will also announce an inquiry into anti-semitism and other forms of racism to be chaired by Shami Chakrabarti.