David Cameron will place Britain’s GCHQ eavesdropping agency and the National Crime Agency (NCA) at the centre of a fight to eliminate “digital hiding places for child abusers”.

A new joint NCA-GCHQ specialist unit is to be established to crack down on paedophiles who are using the so-called “dark web” to disguise their identities and to encrypt illegal images of children that they share with peers in what the prime minister describes as a “horrific crime”.

In a speech on Thursday to the #WeProtect Children online global summit in London, Cameron will say that the new joint unit will combine the technical skills of GCHQ with the investigatory expertise of the NCA to analyse child abuse images hidden on the “dark web”.

Robert Hannigan, the director of GCHQ, said: “GCHQ is using its world-leading capabilities to help the NCA reach into the dark web and bring to justice those who misuse it to harm children. With the NCA, we are committed to eliminating digital hiding places for child abusers.”

The prime minister will highlight the work of GCHQ and the NCA in identifying an individual in the UK who shared child abuse material around the world using chat services and websites in Asia and eastern Europe. GCHQ and the NCA were able to identify the man who was using software designed to maintain anonymity online. He was later sentenced to three years in prison for making and distributing indecent images of children.

Cameron will also unveil new technology to make it harder for paedophiles to move illegal images around the net when websites are closed down. Digital fingerprints, known as “hash values”, of child sex abuse images identified by the Internet Watch Foundation (IWF) will allow the internet multinationals, such as Google, Twitter and Yahoo, to block the images on their services. Google is planning to share with the industry new hashing technology that identifies child abuse videos.

The prime minister will say: “Every time someone chooses to view an online image or a video of a child being abused, they are choosing to participate in a horrific crime. Every single view represents that victim being abused again. They may as well be in the room with them.

“I want to build a better future for our children. The package I am announcing today is a watershed moment in reducing the volume of child abuse images online. It marks significant progress in delivering a truly world-leading response to a global problem.

“The so-called ‘dark-net’ is increasingly used by paedophiles to view sickening images. I want them to hear loud and clear: we are shining a light on the web’s darkest corners; if you are thinking of offending, there will be nowhere for you to hide.”

Peter Wanless, the chief executive of the NSPCC, said: “Child-abuse imagery, increasingly violent and degrading in nature, is an international problem requiring international solutions. The internet does not recognise borders and neither should our efforts to achieve justice for children affected. Governments, technology companies, law enforcement and other organisations all have a part to play in tackling this sick trade.”

The prime minister will highlight global commitments from more than 30 countries to improve the tracking of paedophiles. A new £50m child protection fund will also be established to help victims.

Downing Street highlighted statistics that showed the growing threat of online child abuse. More than 1,000 alleged paedophiles have been arrested in Britain in the last 12 months – five times the 192 arrested in 2012-13. The prime minister will say that Britain has a relatively good record on cracking down on – and deterring – the storing of illegal images. Since 2004 less than 1% of known imagery around the world has been stored in the UK.

Matt Brittin, president of Google in northern and central Europe, said: “We have been working for years to fight child exploitation online and we aggressively remove child sexual abuse imagery from Google products using our image and video-matching technology. Over the past 12 months our algorithm changes and deterrent campaign have already led to a fivefold reduction in a number of child sexual abuse image-related queries in search. We will continue to develop technologies and work with others in the industry to tackle this terrible crime.”