A group of pension funds and asset managers have lined up to lend support to a global campaign led by the New Zealand government, pressuring the tech giants Facebook, Google and Twitter to work harder to block violent and extremist content online.

The campaign, known as the Christchurch Call, was launched on May 15 by New Zealand prime minister Jacinda Ardern and French president Emmanuel Macron, in an effort to prevent repeats of the Christchurch mosque attacks on March 15, in which 51 people were murdered.