Some of Silicon Valley's biggest technology companies have developed an anti-grooming tool aimed at catching paedophiles using social media to target children.

Engineers from Google, Microsoft, Twitter, Facebook and Snap have developed a prototype that can be used to flag potential online conversations between paedophiles and children.

The tool, which has been praised by Home Secretary Sajid Javid in a battle against online child abuse, was built after engineers analysed tens of thousands of real, anonymised conversations to understand patterns used by predators.

The technology was designed to automatically detecting these patterns, create a score for the conversation and alert human moderators to intervene.

Potential conversations between a groomer and a child would be flagged by the system so that a moderator can investigate further.

Home Secretary Sajid Javid said: "We all have responsibility to tackle online child sexual exploitation and the new tool developed during the hackathon is a positive step forward.

"This is just one thing we can do together to combat this appalling crime."

Once complete, it will be rolled out for free to other tech companies that want to deploy it, he confirmed.

None of the companies have yet come forward to develop the product which was created during a two day hackathon co-hosted by Microsoft and the Home Office. Engineers raced against time in the sprint-like computing event to develop the tool.