Google, Facebook and Twitter are set to torpedo Home Office plans to spy on every citizen's emails and website visits.
The internet giants have threatened to block the so-called 'snoopers' charter', which requires them to store all data for a year so that security agencies, police and councils can request its disclosure.
Civil liberty groups claim the powers would create a surveillance state, but Britain's security and intelligence agencies insist they are vital to investigate crime and protect the national interest.
Now the frank testimonies of internet bosses have been released by a cross-party committee of MPs and peers that is scrutinising the draft Communications Data Bill.
They reveal directors from Google, Facebook, Yahoo!, Microsoft and Twitter believe the Bill would breach users' privacy and allow repressive regimes to spy on Britons.
Facebook said it might go to court to resist the new law, while Google and Twitter executives said they could refuse to unlock encrypted data if the Government were to seek the information via third-party providers such as BT.
acebook director Simon Milner accused the Government of using a 'sledgehammer to crack a nut', and claimed the potential for nations with poor human-rights records to obtain data 'should be a real concern'.
Nick Pickles, director of civil-liberty group Big Brother Watch, said: 'How the Home Office thinks these plans are workable in light of such clear criticism is a mystery.'
The Home Office said: 'We hope all major communications companies take their responsibilities to assist law-enforcement seriously.'
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