WhatsApp, Facebook and other social media platforms will be forced to disclose encrypted messages from suspected terrorists, paedophiles and other serious criminals under a new treaty between the UK and the US.

Priti Patel, home secretary, will sign an agreement next month that compels US social media companies to hand over information to the police, security services and prosecutors. The data access agreement, which marks the culmination of four years of intense lobbying by the UK, is seen by Downing Street as an essential tool in the fight against terrorism and sexual abuse.

Ms Patel has previously warned social media companies that they risk empowering terrorists and urged them to take greater responsibility for criminal activity on their platforms. At present the security services are