British spies carry out mass interception of the public's emails and access large databases with individuals' personal details, but their actions are not indiscriminate or unlawful, a powerful committee of lawmakers said on Thursday.
Britain's security agencies have been accused of unfettered snooping on electronic communications since disclosures by US National Security Agency contractor Edward Snowden indicated spies had been hoovering up emails, text messages and internet communications.
Following a lengthy inquiry, the British Parliament's Intelligence and Security Committee (ISC), which acts as a watchdog for the spy agencies, said the bulk collection of data did not amount to blanket surveillance.
According to its heavily-redacted report provided to reporters, spies read "*** thousand items a day," but they only accessed a tiny fraction of everything they scooped up, and the bulk interception of data had exposed previously unknown plots.
"GCHQ is not collecting or reading everyone's emails: they do not have the legal authority, the resources, or the technical capability to do so," said Hazel Blears, one of the committee members and a former Home Secretary (interior minister).
"Only a very tiny percentage of those collected are ever seen by human eyes."
The disclosures by Snowden, who is now living in Moscow, prompted a debate in Britain about how much access the spy agencies - MI5, which deals with domestic matters, MI6, which handles foreign intelligence and the eavesdropping service GCHQ - should have to people's communications data.
Security chiefs and police say new powers to monitor emails and social media websites such as Facebook and Twitter are vital if they are to keep up with militants and criminals, while opponents argue any new laws would breach privacy and amount to a "snoopers' charter."
A British tribunal last month ruled GCHQ had acted unlawfully by accessing data on millions of people in Britain that had been collected by the NSA because the arrangements were secret.
Days later, SIM card maker Gemalto said it believed U.S. and British spies had hacked its systems to steal codes that protect the privacy of billions of mobile phone users.
Prime Minister David Cameron has said his Conservative Party would give the security agencies more power to monitor internet communications if he wins May's national election.
The ISC report revealed for the first time that spies accessed "bulk personal datasets" which contained huge amounts of personal information about Britons, although Blears said they had concluded these were necessary and proportionate.
The ISC also revealed that a handful of spies had been disciplined or sacked for inappropriately accessing these datasets. It gave no further details on those cases.
While rejecting accusations of wrongdoing against the intelligence agencies, the ISC said there needed to be a major overhaul of the laws governing their work to ensure greater transparency and to strengthen privacy protections.
Their report failed to appease privacy campaigners.
"The ISC has repeatedly shown itself as a simple mouthpiece for the spooks - so clueless and ineffective that it's only thanks to Edward Snowden that it had the slightest clue of the agencies' antics," said Shami Chakrabarti, director of human rights group Liberty.