Bomb threats were made to at least a dozen schools today, and four were made yesterday, causing widespread disruption with many of the schools having to evacuate.

The Principals' Federation said the bomb threats originated from an overseas cyberbot.

Police said enquiries were underway today in relation to threats at schools in Masterton, Kaikōura, Greymouth, Queenstown, Levin, Whanganui, Rolleston, Tākaka, Geraldine, Ashburton, Palmerston North and here in Alexandra.

However, police said they did not believe there was a safety risk associated with the threats.

On Tuesday, four North Island high schools received phone bomb threats, in Waikato, Thames, and Gisborne - and had locked down in the wake of the calls.

Principals' Federation president Cherie Taylor-Patel said the hoaxes were distressing for those affected.

She had spoken to the Ministry of Education secretary of education Iona Holsted about the threats.

"The ministry has said that their understanding is that this was actually a cyberbot coming in from overseas. It apparently happened a couple of years ago - so it has happened before, but

obviously it's not something that anyone is prepared for and it's something that no one wants to have happen."

She lauded the efforts of schools to evacuate their students and maintain calm in the face of the threats.

"Today's incidents were really unexpected, unprovoked and really distressing for those communities involved," Taylor-Patel said.

Similar threats had been made against New Zealand schools in recent years.

Today, Awatapu College in Palmerston North said on its Facebook page that it received a bomb threat and evacuated the school.

The college said older students were being sent home while Year 9 students were waiting in the gym, which had been cleared by police. They will be allowed to leave after providing a

permission text from parents or caregivers.

The college's principal, Gary Yeatman, said he believed the threat was made by a person on the other end of the line, though other schools have reported automated messages.

The school had been finishing early anyway due to Covid-19 and staff illness, so students only missed two learning sessions, he said.

He believed the threat was made by a person on the other end of the line, though other schools had reported automated messages.

"Our main office received a phone call around lunchtime claiming there was a bomb on the property," he told RNZ.

"We immediately contacted police and they sent a couple of officers down here and we made the decision, with an abundance of caution, to evacuate the site."

Police had cleared the school and ruled it a hoax about 2pm, he said.

"It appeared to be someone actually on the other end of the line, so it appears to not have been an automated phone call and at that point in time we weren't aware of other schools being

involved.

"My understanding is it was just to say there was a bomb on site and it was going to be detonated. We weren't given a location within the grounds, we weren't given a time."

It was an unneeded and concerning disruption in already interrupted school year, due to Covid-19 and unwell staff, he said.

"So to add to that another reason why we've got to send people away when we want them in class is not ideal. But at the end of the day it is a bomb threat so we can't sit back and ignore it and

think everything will be fine. We have to take them seriously."

Wakatipu High School in Queenstown evacuated its premises for about 80 minutes after receiving a threat around 11.30am.

The school believed it came from an automated overseas number.

A spokesperson said police told the school around 20 similar threats had been received today.

It was decided the threat was not credible and lessons have resumed.

"The kids were fantastic," but the incident was disruptive to the school day, the spokesperson said.

Dunstan High School in nearby Alexandra also received a threat and the school was evacuated.

Police were called and eventually decided there was no threat.

"This unfortunately is in line with a number of similar incidents which have been occurring across the country this week. However, the school will remain vigilant in our responses," the school

said in a message to parents.

Horowhenua College has confirmed that it received a bomb threat, an RNZ staffer said.

Greymouth High School has also said that it received a phone threat.

"We have worked with the police and they have been into school. Police do not believe that there is a safety risk," a spokesperson said.

The school remains open and no students have been sent home.

In Kaikōura three primary schools told RNZ they had not received threats while Kaikōura High School did not wish to comment.

Police said they did not believe there was a safety risk attached to today's incidents.

However, they said police take such threats seriously and were making enquiries to determine the source of the calls.

They thanked the schools involved for following their emergency procedures.

Minister of Police Chris Hipkins had a message for people ringing in bomb threats to schools: Don't be idiots.

He said the police and Ministry of Education had plans in place to deal with threats.