The boss of WhatsApp says it will not "lower the security" of its messenger service. If asked by the government to weaken encryption, it would be "very foolish" to accept, Will Cathcart told the BBC.

End-to-end encryption (E2EE) provides the most robust level of security, because - by design - only the intended recipient holds the key to decrypt the message, which is essential for private communication.

The technology underpins the online exchanges on apps including WhatsApp and Signal and - optionally - on Facebook messenger and Telegram. Only the sender and receiver can read those messages - not law enforcement or the technology giants.