The Netherlands is one of 17 countries to sign up to the Christchurch Call, a pledge to do more to tackle the spread of extremism online.

Eight of the world’s biggest tech companies are among the signatories to the document, which was launched in response to the far-right terror attack in New Zealand that left 51 people dead and was screened live on Facebook.

The US has chosen not to sign the document, saying it may clash with the protection of free speech.