Wikileaks has published details of what it says are wide-ranging hacking tools used by the CIA.
The alleged cyber-weapons are said to include malware that targets Windows, Android, iOS, OSX and Linux computers as well as internet routers.
Some of the software is reported to have been developed in-house, but the UK's MI5 agency is said to have helped build a spyware attack for Samsung TVs.
"We do not comment on the authenticity or content of purported intelligence documents," he said.
A spokesman for the UK Home Office was unable to comment.
Wikileaks said that its source had shared the details with it to prompt a debate into whether the CIA's hacking capabilities had exceeded its mandated powers.
Embarrassment factor - Analysis by BBC's security correspondent Gordon Corera
These latest leaks - which appear to give details of highly sensitive technical methods - will be a huge problem for the CIA.
There is the embarrassment factor - that an agency whose job is to steal other people's secrets has not been able to keep their own.
Then there will be the fear of a loss of intelligence coverage against their targets who may change their behaviour because they now know what the spies can do.
And then there will be the questions over whether the CIA's technical capabilities were too expansive and too secret.
Because many of the initial documents point to capabilities targeting consumer devices, the hardest questions may revolve around what is known as the "equities" problem.
This is when you find a vulnerability in a piece of technology how do you balance the benefit to the public of telling the manufacturer so they can close it and improve everyone's security with the benefit to the spy agency of leaving it in place so they can exploit it to collect intelligence.
The NSA has already faced questions about whether it has this balance right when many of its secrets were revealed by Edward Snowden, and now it may be the CIA's turn.
Read more from Gordon
Hacked TVs
The effort to compromise Samsung's F8000 range of smart TVs was codenamed Weeping Angel, according to documents dated June 2014.
They describe the creation of a "fake-off" mode, designed to fool users into believing that their screens had been switched off.
Instead, the documents indicate, infected sets were made to covertly record audio, which would later be transferred over the internet to CIA computer servers once the TVs were fully switched back on, allowing their wi-fi links to re-establish.
Under a "future work" section, it is suggested that video snapshots might also be taken and the wi-fi limitation be overcome.