LONDON – British officials have demanded tech firms do much more to give police access to smartphone communications following last week’s Westminster attack, just months after new laws gave security services broader powers.

However, they have yet to spell out clearly whether the government wants them to weaken encrypted services such as WhatsApp or are simply asking for ways to gain access to phones in their possession to recover suspects’ communications.

British media have reported that shortly before launching the attack last Wednesday, Khalid Masood used encrypted messaging via WhatsApp which investigators cannot read.

Police have been trying to determine whether Masood – who killed four people including a policeman near parliament in London before being shot dead – acted alone.

WhatsApp and Facebook messenger icons are seen on an iPhone. (Photo: Reuters)

Neil Basu, a top counter-terrorism policeman, said his communications on the day of the attack are the main line of inquiry and said he had a clear interest in jihadist armed struggle.

A spokesman for Prime Minister Theresa May said on Monday she wanted tech firms such as Facebook, Apple and Google to find ways to give security services access to messages on phones, but was leaving it up to companies to sort out how.

British officials plan to meet US tech executives on Thursday to insist they do more to crack down on extremist content on websites such as Google’s YouTube, following a revolt over the issue by major advertisers, including British government agencies.

They also plan to press Silicon Valley leaders to help monitor communications by potential attackers.

“If there are circumstances where law enforcement agencies need to be able to access the contents, they should be able to do so. How that is achieved, I think, is a matter for the talks later in the week,” May’s spokesman said.

The criticisms are the latest moves by European countries to rein in US tech giants, pressing them do more to stop hate speech and extremist activities online. Germany is planning a new law calling for social networks like Facebook and Twitter to remove hate speech quickly or face fines of up to 50 million euros (A$71 million).

– Reuters