WhatsApp has begun encrypting all communications between its one-billion users.

It means messages sent using the service are scrambled - and can only been decoded by the recipient's device.

It means intercepted messages can't be read by police or security services.

The news comes just weeks after the FBI confirmed it had found a way to break into an iPhone used by one of the San Bernardino attackers, without the help of Apple.

The firm had refused to unlock it, saying the new software it would have to write could undermine security for everyone.

A U.S. court hearing over whether Apple should be forced to comply has now been cancelled.