A spyware scanner released by Amnesty International will allow journalists and human rights activists to see if their government is snooping on them.

Though Detekt cannot guarantee spyware does not reside on your machine, it is described as a "best effort" attempt to counter intrusion on computers and is hoped to provoke a debate on the use of surveillance tools.

Marek Marczynski, head of military, security and police at Amnesty, said: "Detekt is a simple tool that will alert activists to such intrusions so they can take action.

"It represents a strike back against governments who are using information obtained through surveillance to arbitrarily detain, illegally arrest and even torture human rights defenders and journalists."

Information leaked by NSA whistleblower Edward Snowden showed that the British and American governments were capable of collecting a vast array of data from phones, keyboards, cameras and microphones connected to computers. This is what Detekt is looking to undermine.

The Coalition Against Unlawful Surveillance Exports now estimates the annual global trade in surveillance technologies to be worth US$5 billion, and figure that is thought to be growing.

Eva Galperin, global policy analyst at the Electronic Frontier Foundation, which is backing the tool, said: "Detekt makes it easy for at-risk users to check their PCs for possible infection by this spyware, which often goes undetected by existing commercial anti-virus products."