LONDON: Google, Facebook, Microsoft and Twitter have promised to work together to combat online extremist content and terrorist propaganda, following a meeting with the British Home Secretary.

Senior executives from the tech companies met Amber Rudd last Thursday, along with representatives from some smaller firms, to discuss collective measures against those who seek to do harm, Bloomberg reported.

The meeting came just a week after Khalid Masood's murderous car and knife rampage on the streets of London that left four people dead, including an unarmed policeman who was guarding Parliament.

Amber Rudd had also used an interview a few days earlier with the BBC to insist the police and intelligence agencies should have access to Facebook-owned WhatsApp and other encrypted messaging services.

She said it was "completely unacceptable" for the authorities to be unable to read messages protected by end-to-end encryption.

Following her meeting with Google and the other tech companies, they promised to explore options for a cross-industry forum and to "urgently improve" their collaboration on technical tools to identify and remove terrorist propaganda.

"Our companies are committed to making our platforms a hostile space for those who seek to do harm, and we have been working on this issue for several years," the companies said in a joint statement. "We share the government's commitment to ensuring terrorists do not have a voice online."

Meanwhile, Amber Rudd said: "In taking forward this work I’d like to see the industry to go further and faster in not only removing online terrorist content but stopping it going up in the first place.

"I'd also like to see more support for smaller and emerging platforms to do this as well, so they can no longer be seen as an alternative shop floor by those who want to do us harm."

The summit held at the highest levels of the British government comes as Google, in particular, continues to be criticised over its placement of ads on extremist and other inappropriate sites.

The ongoing controversy also extends to wider concerns about transparency and trust in the digital advertising ecosystem, and this has prompted the CEO of the Internet Advertising Bureau (UK) to add his voice.

Writing in The Drum, the IAB's Jon Mew stated that there are some simple principles that the industry should apply to digital that could "make a massive difference" to the issues being faced while also making the channel more effective.

He said the industry must stop serving ads that annoy people and he referred to updated guidance that the Coalition for Better Ads published very recently.

Mew also criticised some advertisers for the way they use metrics, arguing that they should stop chasing click-through rates and instead focus on "pushing towards measuring long-term uplifts in brand perceptions and sales".

Finally, he reminded advertisers of the importance of using third-party verification, such as the guidance offered by JICWEBS, a joint industry committee.

Data sourced from Bloomberg, BBC, The Drum; additional content by WARC staff