Britain's democratic oversight of the intelligence and security agencies has "rescinded to the point of extinction", the president of the Liberal Democrats has said.
In a piece for Politics.co.uk, Tim Farron cast doubts on the ability of the Intelligence and Security Committee (ISC), which includes former Lib Dem leader Ming Campbell, to effectively scrutinise the work of the intelligence agencies.
"Pervasive surveillance of our entire digital lives has been allowed to take place without prior knowledge, debate or consent," he wrote.
"The ISC is a group of the great and good. Experienced hands. 'Sound men' as Sir Humphrey might put it.
"No-one is naive enough to expect state secrets to be discussed publically in front of a TV audience. But only a fool would think we are re-assured by the appearance of a mandarin quietly saying 'trust me, everything is alright'.
"When the programs systemically collecting your personal information are so secret that even the Cabinet are not aware of their existence, our democratic oversight has rescinded to the point of extinction."
Farron's comments suggest a gradual shift in the Lib Dem response to the row over state surveillance of the public's electronic communications, which began with a stream of revelations from CIA analyst Edward Snowden.
The Lib Dems have a strong track record on privacy and civil liberties issues, but they have struggled to voice their concern over intelligence powers at a time when they wants to project an image of being a party of government.
Nick Clegg is known to be privately uncomfortable with the revelations and is planning on giving the issue greater priority in the new year.
Today, Theresa May refused a request by the home affairs committee to question the head of MI5, Andrew Parker, on the basis she did not believe "it would be appropriate or necessary for the oversight provided by the ISC to be duplicated by another committee".
The ISC usually meets in secret. A public meeting with intelligence bosses earlier this year was widely derided by critics for how leniently it was conducted.