UK home secretary Amber Rudd had called for opening of encryption of WhatsApp messaging system to security services and urged online companies to be more aggressive in shutting down sites exploited by terrorists.
The call comes after it was revealed that Khalid Masood, who killed four people in London last week, had used WhatsApp shortly before he began his attack. Rudd said the company needed to do more to help fight terrorism.
''It's completely unacceptable'' that messages can't be opened, Rudd told the BBC's ''Andrew Marr Show'' yesterday. ''We need to make sure that our intelligence services have the ability to get into encrypted services like WhatsApp.''
Following the attack, online companies had been criticised by government ministers for not doing enough to stop the spread of hate messages. Writing in the Sunday Telegraph, Rudd said the internet was ''serving as a conduit, inciting and inspiring violence, and spreading extremist ideology.'' Foreign secretary Boris Johnson told the Sunday Times that ''They need to stop just making money out of prurient violent material.''
According to Rudd she would be meeting with executives of internet companies this week.
''They're going to get a lot more than a ticking off," Rudd said on Sky's ''Sophy Ridge on Sunday'' programme.
According to commentators, Rudd's call for a "back door" system to allow authorities to retrieve information was likely to meet resistance from the tech industry, which had faced previous law enforcement demands for access to data after major attacks.
In the US Apple fought the FBI's request for the passcodes required for unlocking an iPhone that had been used by one of the perpetrators in the 2015 extremist attack in San Bernardino, California.
Police are trying to identify the attacker's motive and find possible accomplices.
According to experts, the message could provide clues to his state of mind and his social media contacts.
According to Rudd these kind of attacks could be prevented if authorities could penetrate encrypted services after obtaining warrants similar to the ones used to listen in on telephone calls or in snail mail days to steam open letters and read their contents.