Cameron secured the backing of all main parties in the country for the highly unusual move after the European Court of Justice struck down existing powers.
While civil liberties campaigners have warned that it will invade people's privacy, Cameron defended the move in a joint news conference with Deputy Prime Minister Nick Clegg, saying it was about maintaining existing capabilities - not introducing new snooping laws.
"We face real and credible threats to our security from serious and organised crime, from the activity of paedophiles, from the collapse of Syria, the growth of Isis in Iraq and al Shabab in East Africa," Cameron said.
"I want to be very clear that we are not introducing new powers or capabilities - that is not for this Parliament."
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"This is about restoring two vital measures ensuring that our law enforcement and intelligence agencies maintain the right tools to keep us all safe."
The emergency Data Retention and Investigation Powers Bill would also "clarify" the law on bugging of suspects' phones by the police and security services, when the home secretary issues a warrant, after service providers were turning down requests.
A former senior diplomat will also be appointed to work with other nations to speed up the "lawful and justified" transfer of data across borders.
Cameron also said he had reached an agreement with Labour leader Ed Miliband for a wider review of the surveillance powers needed by the security services, to report after the next election.