Human rights group Privacy International has filed a legal complaint against GCHQ.
The group says that the British spooks installed malware on millions of devices without their owners' permission.
The complaint, filed Tuesday by Privacy International, accused the Government Communications Headquarters (GCHQ) of surveillance techniques that were "incompatible with democratic principles and human rights standards."
The privacy watchdog was miffed that GCHQ installed hacking programs such as Nosey Smurf, Tracker Smurf, and Foggybottom on computers, mobile phones, and webcams to secretly record users' doings.
"In allowing GCHQ to extract a huge amount of information (current and historical), much of which an individual may never have chosen to share with anybody, and to turn a user's own devices against him by coopting them as instruments of video and audio surveillance, it is at least as intrusive as searching a person's house and installing bugs so as to enable continued monitoring," the complaint states.
The complaint adds that the actions of GCHQ were more intrusive because of the amount of information generated and stored by computers and mobile devices.
The complaint follows documents leaked by former NSA contractor Edward Snowden.
In its 21-page complaint the UK-based watchdog, Privacy International claims the techniques allegedly used by the UK's counterpart to the NSA violate European human rights law and requested that the alleged practice be stopped.
Eric King, Privacy International's deputy director, said in a statement that the hacking programs being undertaken by GCHQ were the same as a government entering your house, rummaging through your filing cabinets, diaries, journals and correspondence, before planting bugs in every room you enter.