Islamic State retaliation threat: New Zealand's darkest day casting a long shadow

Jihadist groups around the world, including the Islamic State (IS), are threatening retaliation for the Christchurch attacks, calling on Muslims to take vengeance.

Visiting Christchurch on Wednesday, Prime Minister Jacinda Ardern said that while the Muslim community in New Zealand rejects that rhetoric, security agencies are taking all threats seriously. 

The threats cast a shadow over a moving welcome for Ardern from students at Cashmere High in Christchurch, where two students were killed in Friday's attacks.

The school has been devastated by the attack. Two students were killed, as well as a former student, and also fathers of students were killed and injured. 

"You know some of the young people who died - it's them we need to honour," Ardern told the students. 

"Yes, there will be interest in the terrorist that did this, don't dwell on him, who he is, dwell on your friends [who are the] most important people right now."

The alleged gunman's video of the attack is still available online. In light of that, Ardern raised the benefits of social media in promoting vigils, but also warned of the risks. 

When asked by a student how she was feeling, Ardern thanked the student, and told them: "I'm very sad."

The Prime Minister left the school to meet some of those who were first at the scene of the attack. 

"Thank you for doing what you do on our darkest days," Ardern said. 

And our darkest day is casting a long shadow. 

Jihadist groups are threatening retaliation for the attack, with IS issuing a call to arms. After six months' silence, the terrorist group's spokesman released a 44-minute audio clip. 

"The scenes of the massacres in the two mosques should wake up those who were fooled and should incite the supporters of the 'caliphate' who live there to avenge their religion," the clip says. 

When asked about it, Ardern said: "I have not heard that language from the Muslim community - I have heard the completely opposite."

It was a rejection of violence and hate no matter where it comes from. But New Zealand is taking the threats very seriously. 

"We know given how monstrous the events were on Friday, that it was not unexpected that somewhere in the world somebody would make a comment like that," Justice Minister Andrew Little said. 

"People can be reassured that our authorities, the spy agencies, the police, and other authorities are alert to that and preventing retaliatory action is foremost amongst their concerns."

Wednesday was the Prime Minister's second trip to Christchurch since the attack, and it will not be the last.