Spies would be foolish to ignore bulk email data - Rifkind
Intelligence agencies would be "foolish" not to use modern technology allowing them to track terrorist plots, the chairman of Parliament's intelligence committee has said.
Sir Malcolm Rifkind's comments come as eight internet firms warned the US government to reform its collection of bulk data via emails.
He called for "proportionality" between security and individual liberty.
But the emails were read by computer and most were "not seen by human eye".
In the US, eight firms - Google, Apple, Facebook, Twitter, AOL, Microsoft, LinkedIn, and Yahoo - have formed an alliance called Reform Government Surveillance.
The group has written a letter to President Obama and the US Congress arguing that current surveillance practice "undermines the freedom" of people.
But Sir Malcolm, a Conservative MP and chairman of the Intelligence and Security Committee, told BBC Radio 4's Today programme: "When bulk data is collected, that doesn't mean people are sitting reading everybody's emails. The companies understand that, but not necessarily everybody outside the companies."
He added: "The issue that we all want to address is one of proportionality. The onus has to be on the governments, not so much the agencies."
Sir Malcolm also said: "Is the benefit that's achieved in the battle against terrorism of such significance that it justifies intrusion on privacy, not because people read your emails but because these emails are processed by computers so they can identify the tiny number that correlate to terrorists."
The move by the eight internet firms comes after whistle-blower Edward Snowden leaked information about surveillance carried out by the US government.
Mr Snowden, an ex-US intelligence contractor, leaked documents to the media highlighting the various methods used by agencies to gather information.
When asked about the use of computers to scan enormous numbers of emails to look for patterns of behaviour suggesting terrorist activity, Sir Malcolm replied: "I think there's a perfectly reasonable argument for saying that, if a human eye is not reading innocent people's emails, then we do have to extract from this vast number of internet communications that tiny number that relate to serious terrorist plots.
"So I start off by recognising that, in the modern world, the terrorists use all the technology available to them.
"It would be foolish for the intelligence agencies in free societies not to start by using that technology.
"However, they cannot be allowed to determine themselves what the rules are. They don't at the moment. Parliament has laid down rules. What we want to look at is the question of proportionality."
Sir Malcolm's committee is carrying out an inquiry into UK intelligence agencies' access to people's private information.