The news comes as some US surveillance powers expire and tensions rise between the US government and the tech community over the use of strong encryption.

Strong encryption refers to data coded in such a way that it cannot be understood by anyone who does not have the correct key to decrypt it.

It can help internet users keep their sensitive communications safe online — but some people believe it poses a potential security risk, as it cannot be decrypted by authorities even with a search warrant.

Following revelations of mass government surveillance by exiled whistleblower Edward Snowden over the last few years, big tech companies have increasingly incorporated strong encryption into their products.

This hardened stance is frustrating law enforcement, who fear they will lose access to vital evidence. When Apple announced it would implement strong encryption on its iOS mobile operating system, for example, one senior US police officer claimed the iPhone "will become the phone of choice for the pedophile." But Apple argues that it is imperative that it protects users' privacy, with CEO Tim Cook saying the company has "never worked with any government agency from any country to create a backdoor in any of our products or services... And we never will."