Internet and social media companies have come under fire over their failure to remove extremist material from the web.

In an interview in the Sunday Times, Foreign Secretary Boris Johnson attacked internet giants, accusing them of "not acting when they are tipped off", while Home Secretary Amber Rudd, writing in the Sunday Telegraph, said companies needed to be more "proactive".

Mr Johnson accused internet companies of a "disgusting" failure and called on companies like Facebook and Twitter to develop new technology to detect and remove jihadist and other extreme material.

"I'm furious about it. It's disgusting," he said. "They need to stop just making money out of prurient violent material."

Jihadist material is accessible in cyberspace. In the days ahead of the Westminster attack, internet giant Google had already been forced to promise it would take a "tougher stance" on hateful online content.

That followed the recent outcry and boycotts from advertisers after it became apparent their content was appearing alongside extreme material.

Mr Johnson said online media companies were "not acting when they are tipped off".

"Evil flourishes when good men do nothing - and that's what's happening here. They are putting up adverts next to it," he said.

Home Secretary Amber Rudd, made similar criticisms in the Sunday Telegraph.

"Each attack confirms again the role that the internet is playing in serving as a conduit, inciting and inspiring violence, and spreading extremist ideology of all kinds," she wrote.

"But we can't tackle it by ourselves ... We need [social media companies] to take a more proactive and leading role in tackling the terrorist abuse of their platforms."

An investigation by the Sunday Mirror uncovered a host of messages encouraging extremist violence exchanged on the encrypted Telegram messaging site.

They included an image of a sword-bearing jihadi fighter standing in front of a burning Big Ben, sent weeks before the Westminster attack.