British spies want 'backdoor' access to encrypted messages on social media to prevent terror threats and child abuse.
Officials from the UK, US, Canada, Australia and New Zealand – known as the 'Five Eyes' intelligence alliance – are meeting in London to discuss being able to get 'lawful access' to WhatsApp discussions that could be linked to crime.
It comes after the London Bridge terrorists used WhatsApp to discuss plans which British officials say helped prevent the 2017 plot that killed eight people from being identified.
One such technique suggested by the UK intelligence agency GCHQ is to allow its agents to be 'silently' added to chats or calls so they can observe the conversation without being detected.
Encryption is increasingly being used to protect privacy on social media platforms, with WhatsApp already using it, Facebook due to introduce it to its Messenger app and Google exploring 'encrypted browsers'.
Meanwhile new Home Secretary Priti Patel has pledged to strengthen Britain's links with its Five Eyes allies and confirmed they would also be discussing ways to bolster border defences and tackle foreign 'Islamist' threats.
A spokesperson for the Home Office said: 'We need to ensure that our law enforcement and security and intelligence agencies are able to gain lawful and exceptional access to the information they need.'
Five Eyes intelligence chiefs what tech firms to do more to help them and say such access would only be reserved for 'exceptional cases' where there was a 'serious threat of terrorism or child sexual abuse', with a judge or government minister having the final sign-off.
In a paper produced at the end of 2018 GCHQ and National Cyber Security centre directors Ian Levy and Crispin Robinson said it would be 'relatively easy' for a messaging service to provide 'silent' access.
The paper said: 'You end up with everything still being end-to-end encrypted, but there's an extra 'end' on this particular communication.
'This sort of solution seems to be no more intrusive than the virtual crocodile clips that our democratically elected representatives and judiciary authorise today in traditional voice intercept solutions, and certainly doesn't give any government power they shouldn't have.'
The pair added it would be exceptional because 'almost all users would not be affected'.
But the proposal was condemned as a 'threat to human rights' and opposed by 50 organisations including Apple, WhatsApp and campaigners Liberty in an open letter.
The letter said: 'The overwhelming majority of users rely on their confidence in reputable providers to perform authentication functions and verify that the participants in a conversation are the people they think they are, and only those people.
'The GCHQ's ghost proposal completely undermines this trust relationship and the authentication process.'
But the intelligence agencies have been backed up by children's charity the NSPCC amid concerns child abuse images online have increased tenfold since 2013.
Andy Burrows, NSPCC head of child safety online policy, told the Telegraph: 'Encryption will make it fundamentally more difficult for law enforcement to uncover grooming and child abuse imagery.
'There is a growing case for police to be given proportionate powers to investigate these increasingly complex and hidden abuse crimes.'
Facebook declined to comment before the meeting today, while MailOnline has contacted WhatsApp for comment.
Speaking about the summit, Ms Patel said: 'This is an exciting moment for the UK as we look to respond to a challenging and rapidly changing global environment, strengthening our influence on the world stage to promote our prosperity and security.
'The UK is a global leader on national security and child protection and we are committed to working with our close partners on shared challenges.'