United Kingdom Prime Minister David Cameron will move to outlaw forms of digital communication that cannot be read by law-enforcement and intelligence agencies if he wins the next general election.
Such a move could see messaging platforms that encrypt their data, including apps such as WhatsApp and Snapchat, along with Apple's iMessage and FaceTime, blocked under the proposed legislation.
Cameron said at an event in the East Midlands on Monday that such a move would be "absolutely right" for a modern liberal democracy, reported The Independent.
"In our country, do we want to allow a means of communication between people, which even in extremis, with a signed warrant from the home secretary personally, that we cannot read?" said Cameron. "Up until now, governments of this country have said no, we must not have such a means of communication.
"That is why, in extremis, it has been possible to read someone's letter. That is why ... it's been possible to listen in to someone's telephone call. That is why the same has been applied to mobile communications.
"But the question remains, are we going to allow a means of communication where it simply isn't possible to do that? My answer is no, we are not. The first duty of any government is to keep our count and our people safe," he said.
The comments follow Cameron's pledge to introduce legislation dubbed the "snoopers' charter" following the unity march in Paris on Sunday, held in the wake of the Charlie Hebdo attack by Islamist terrorists in the city on January 7.
"The attacks in Paris once again demonstrated the scale of the terrorist threat that we face and the need to have robust powers through our intelligence agencies and security agencies and policing in order to keep our people safe," said Cameron. "And the powers that I believe we need, whether on communications data or on the content of communications, I'm very comfortable that those are absolutely right for a modern, liberal democracy."
Just a day after the Charlie Hebdo attack, the head of MI5, Andrew Parker, reiterated the importance of communications interception in the fight against terrorism, and cautioned that changing technology is making it harder for agencies to keep tabs on such communications.
"Interception of communications, which includes listening to the calls made on a telephone, or opening and reading the contents of emails, form a critical part in the Security and Intelligence Agencies' tool kit," said Parker in a speech to the Royal United Services Institute in London on January 8. "Changes in the technology that people are using to communicate are making it harder for the agencies to maintain the capability to intercept the communications of terrorists.
"Wherever we lose visibility of what they are saying to each other, so our ability to understand and mitigate the threat that they pose is reduced," he said.
Cameron suggested that although the UK parliament had legislated recently on communications data, that legislation would fall away automatically in 2016, and the government would have to legislate again at that time.
In July, Britain's parliament voted in favour of emergency legislation to allow police and security services to continue accessing internet and mobile phone data, despite a ruling in April by the European Court of Justice that existing data-retention laws across Europe breached citizens' rights to privacy.
Civil liberties campaigners have criticised the Bill as being intrusive, saying it could infringe on privacy rights.
However, Cameron said that the potential introduction of legislation to safeguard against forms of digital communication that cannot be read by law-enforcement bodies would be introduced with a reasonable amount of oversight around what information agencies could access under the scheme.
"Let me stress again, this cannot happen unless the home secretary personally signs a warrant. We have a better system for safeguarding this very intrusive power than probably any other country that I can think of," he said.
Despite Cameron's assurances, Labour's Shadow Home Secretary Yvette Cooper said in a statement that any new legislation would have to be balanced with appropriate oversight mechanisms.
"The capabilities of the intelligence agencies and law enforcement must keep pace with changing and emerging technology. So too must the oversight arrangements," said Cooper. "With proper warrants in place, the agencies need to be able to continue to be able to look at the content of communications of those feared to be plotting terrorist attacks. And there must continue to be safeguards to protect innocent people's privacy."
The move to revive the so-called "snoopers' charter" comes as internet and communications companies work to protect their users' personal information through mechanisms such as encryption in the wake of Edward Snowden's NSA surveillance revelations.
Cameron, however, expressed concern that the development of new technologies could further hamper the government's abilities to access information that he said it needs to combat terrorism.
"Will we be able to access the content of communication as the internet and new ways of communicating develop?" he said. "What I can say is that if I'm prime minister, I will make sure that it is a comprehensive piece of legislation that makes sure we do not allow terrorists safe space to communicate with each other.
"That is the key principle. Do we allow safe spaces for them to talk to each other? I say no, we don't, and we should legislate accordingly," he said.
The prime minister's latest statements echo comments he made to a joint a sitting of the Australian parliament in November that businesses have a social responsibility to clamp down on extremist content on the internet.
"We must not allow the internet to be an ungoverned space," Cameron told parliament at the time.
On Monday, Australian Attorney-General George Brandis linked the terrorist attacks in Paris, along with the earlier siege in Sydney, to the Australian government's desire to pass legislation requiring telecommunications companies to retain customer metadata for a minimum of two years.
The fourth so-called "tranche" of the federal government's anti-terror laws is likely to be debated in parliament in March.