New Zealand is in shock and mourning after the worst attack in its modern history, in which 49 Muslim worshippers in two mosques were shot and killed during Friday prayers.

Police in Christchurch arrested Brenton Tarrant. He has appeared in court on charges of murder.

After the attack was livestreamed on Facebook, detectives are focusing on the perpetrator's online activities and a so-called "manifesto" full of far-right, ultranationalist and anti-Muslim views.

So what should be done to stop hate speech online?

Presenter: Adrian Finighan


Tahir Nawaz - president, the International Muslim Association of New Zealand

Raphael Bossong - research associate, German Institute for International and Security Affairs

Nolen Gertz - technology ethics expert 

Source: Al Jazeera News