(Bloomberg) -- Social media platforms based in the U.S. including Facebook and WhatsApp will be forced to share users’ encrypted messages with British police under a new treaty between the two countries, according to a person familiar with the matter.

The accord, which is set to be signed by next month, will compel social media firms to share information to support investigations into individuals suspected of serious criminal offenses including terrorism and pedophilia, the person said.

Priti Patel, the U.K.’s home secretary, has previously warned that Facebook’s plan to enable users to send end-to-end encrypted messages would benefit criminals, and called on social media firms to develop “back doors” to give intelligence agencies access to their messaging platforms.

The U.K. and the U.S. have agreed not to investigate each other’s citizens as part of the deal, while the U.S. won’t be able to use information obtained from British firms in any cases carrying the death penalty.

Details of the accord were reported earlier by the Times.

To contact the reporters on this story: Kitty Donaldson in London at kdonaldson1@bloomberg.net;Mark Burton in London at mburton51@bloomberg.net

To contact the editors responsible for this story: Andrew Davis at abdavis@bloomberg.net, James Amott

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