Human rights experts and technology groups have launched a new tool allowing members of the public to scan their computers for surveillance spyware used by governments.

Amnesty says Detekt is the first tool freely available that will allow activists and journalists to find out if their PCs are being monitored without their knowledge.

Marek Marczynski, head of military, security and police at Amnesty, said: “Governments are increasingly using dangerous and sophisticated technology that allows them to read activists’ and journalists’ private emails and remotely turn on their computer’s camera or microphone to secretly record their activities. They use the technology in a cowardly attempt to prevent abuses from being exposed. Detekt is a simple tool that will alert activists to such intrusions so they can take action.”

Trade in communication surveillance technologies has grown massively in recent years, with private companies sell off-the-shelf equipment that allows governments to snoop on millions of emails, text messages and phone calls, according to an investigation by the Guardian last year. The Coalition Against Unlawful Surveillance Exports, of which Amnesty is a member, estimates the annual global trade in surveillance technologies is worth more than £3bn and growing.

Some surveillance technology is widely available on the internet, while other more sophisticated alternatives are developed by private companies and sold to state law enforcement and intelligence agencies in countries that persistently commit human rights violations.

Detekt was developed by Germany-based security researcher Claudio Guarnieri after discussions with human rights activists. It will be launched on Thursday in partnership with Amnesty International, British charity Privacy International, German civil rights group Digitale Gesellschaft and US digital rights group the Electronic Frontier Foundation.

Amnesty wants governments to establish strict trade controls requiring national authorities to assess the risk that surveillance equipment would be used to violate human rights before authorising any transfer, in a similar manner to how the arms trade is controlled.

Marczynski added: “Detekt is a great tool which can help activists stay safe but ultimately the only way to prevent these technologies from being used to violate or abuse human rights is to establish and enforce strict controls on their use and trade.”

Amnesty will promote the new software, which is free and open-source, among their activists around the world.

Marczynski said: “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.”

• This article was amended on 20 November 2014. An earlier version said incorrectly that Claudio Guarnieri was German, and that the Detekt software scanned computers and phones. The headline was also amended; an earlier version began “Amnesty launches Detekt tool to scan for state spyware on phones and PCs”. And the picture and caption were changed; the previous picture was of smartphones.