March 18 (Reuters) - A consortium of global technology firms has shared on its collective database the digital fingerprints of more than 800 versions of the video of New Zealand's mass shootings that killed 50 people, it said on Monday.

While it was not the first internet broadcast of a violent crime, the livestream of the massacre showed that stopping gory footage from spreading online persists as a major challenge for tech companies despite years of investment.

Last Friday, social media users intent on sharing the mosque shooting video were said to have used several methods to create a new version with a digital fingerprint different from the original, so as to evade companies' detection systems.

"This incident highlights the importance of industry cooperation regarding the range of terrorists and violent extremists operating online," the grouping, which includes Facebook Inc, Alphabet Inc's Google and Twitter Inc, said https://www.gifct.org/press/industry-cooperation-combat-violent-extremism-all-its-forms of the attack.

The gunman who attacked the two mosques in New Zealand live-streamed the attacks on Facebook for 17 minutes using an app designed for extreme sports enthusiasts, with copies still being shared on social media hours later.

Late on Saturday, Facebook, the world's largest social media network with around 2.3 billion monthly users around the world, said it had removed 1.5 million videos within 24 hours after the Christchurch attack.

New Zealand Prime Minister Jacinda Ardern has said she wants to discuss live streaming with Facebook, and some of the country's firms are considering whether to pull advertising from social media.

The Global Internet Forum to Counter Terrorism (GIFCT) was created in 2017 under pressure from governments in Europe and the United States after a spate of deadly attacks.

It shares technical solutions for the removal of terrorist content, commissions research to assist its efforts to fight such content and works more with counter-terrorism experts.

(Reporting by Munsif Vengattil in Bengaluru; Editing by Clarence Fernandez)