A computer forensic expert is warning an underground group of cyber teens bent on causing mayhem may be behind the spate of hoax bomb threats causing havoc in New Zealand schools this week.

Special Tactics managing director Daniel Ayers is warning authorities to brace for more bogus bomb scares as a group operating on the dark web known as "evacuators" target schools to bring about as much chaos as possible.

But police refused to speculate on the involvement of the role of the Evacuation Squad saying police were investigating the source of calls made to New Zealand schools over the past couple of days.

"As there is an ongoing investigation, and in order to not prejudice any of our inquiries, police are unable to comment on the specifics of the case," said a spokesman.


Mr Ayers said the group was spreading its reach internationally through an online appeal for teenagers to nominate their schools for "swatting", a term used for making a false complaint that leads to high level police response.

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Last month the group posted a note on the anonymous website Pastebin that it was accepting $5 to $20 Bitcoin payments to call in bomb threats at schools, businesses and sport grounds.

"Until March, 2015, you may send in requests for your school/work/business/etc to be sent a bomb threat. After March 1st, of 2015, we will be accepting Bitcoin only as payment," the group wrote.

The fees range from $5 for schools through to $50 for major sports events.

This week there were at least 33 primary, secondary and intermediate schools forced into lockdown after malicious calls were made to principals threatening live bombs in schoolyards across the country.

In each case the call appears as made locally using a voice over internet technology (VoIP) that converts international calls into local phone calls.

Mr Ayers told the Herald it was important for the loophole to be closed at a Government level.

"What's going on at the moment is so harmful to society that there needs to be a regulatory response to it to either make it impossible to make voice over IP calls out of or into New Zealand or at least strengthen the protection so if they do things they shouldn't they can be stopped."

He said the sudden explosion of hoax threats could have been requested from local school children or simply the group spreading its reach from across the Tasman where it had recently caused a headache for authorities in recent weeks.

"What we don't know is whether it's spreading because this group is bored and they just want to find more targets or it's spreading because kids at various places, particularly schools, are contacting the group and inviting them to do it to their school because they think it would be fun to get them out of class.

"That says to me the people who are providing this service are teenage kids and the people who are requesting the service are teenage kids."

He said it was very difficult to know how to tackle the issue and whether police should dismiss the deluge of hoax bomb threats.

"On one hand there's a lot of disruption coming from these events and it's tempting to say let's eliminate the disruption by ignoring the calls. On the other hand most bomb threats are hoaxes, but not all of them are, and it's very tough to make that decision."