MI5 and the CIA colluded to develop viruses to turn Samsung smart TVs into household bugs, according to "leaked" intelligence documents published by WikiLeaks.
The documents - said to have come from the CIA's Centre for Cyber Intelligence - allegedly show that a CIA branch worked with MI5 on a project to "infest smart TVs, transforming them into covert microphones".
The so-called "weeping angel" programme would trick users into thinking their TV was off when it was actually on, it is claimed.
WikiLeaks says the documents show smart TVs were then used as a bug "recording conversations in the room and sending them over the internet to a covert CIA server".
WikiLeaks described the development as an "emblematic realisation" of George Orwell's 1984 - a novel which imagines how TV screens could be used to monitor the every move of citizens.
It is claimed a different CIA unit produced malware to "infest, control and exfiltrate" data from iPhones and iPads, while a similar team is said to target Google's Android operating system - allowing agents to "bypass" the encryption of messaging apps like Signal, WhatsApp, and Telegram.
:: What is in WikiLeaks' 'Vault 7' release of 'CIA' documents?
WikiLeaks adds that the US intelligence agency "runs a very substantial effort to infect and control Microsoft Windows users with its malware".
Meanwhile, it is also alleged the CIA looked into "infecting the vehicle control systems used by modern cars and trucks", allowing it to "engage in nearly undetectable assassinations".
The CIA said it would not comment "on the authenticity or content of purported intelligence documents".
WikiLeaks says it obtained the "Vault 7" collection of 8,761 documents and files after they were circulated among former US government hackers and contractors "in an unauthorised manner".
It added that "Vault 7" is the largest intelligence leak in the CIA's history which shows the "scope and direction" of the agency's "global covert hacking programme".
In a statement, WikiLeaks editor Julian Assange described the spread of cyber weapons as an "extreme risk".
He said: "Comparisons can be drawn between the uncontrolled proliferation of such 'weapons', which results from the inability to contain them combined with their high market value, and the global arms trade."
WikiLeaks and its allies have embarrassed Washington before.
Previous releases of classified material have included hundreds of thousands of documents from the Pentagon and the State Department.