New Zealand facing unprecedented cyber attacks: Minister

New Zealand's justice minister said the nation is confronting cyber attacks on an unprecedented scale, targeting everything from the stock market to the weather service.

Andrew Little said in an interview with The Associated Press on Wednesday that tracking down the perpetrators of the attacks in recent weeks would be extremely difficult, as the distributed denial of service attacks are being routed through thousands of computers.

One line of investigation is the emails sent to people in some of the targeted organisations demanding a ransom in exchange for stopping the attacks, Little said.

The official advice is to never, ever pay a ransom.

Little said he's been told that the sheer volume of data used by the attackers is unprecedented. New Zealand's foreign spy agency, the Government Communications Security Bureau, is helping with the investigation and working to protect companies targeted in what it says appears to be part of a global campaign.

The attacks stopped share trading for up to several hours at a time over four days last week.

Private company NZX, which hosts the market, said it halted trading to maintain market integrity because the attacks prevented it from publishing market announcements.

Little said the attackers had found vulnerabilities in the stock market's operations.

That motivated them to continue the attack, and they picked on other organisations as well, he said.

One of those was the bank TSB, which was hit Tuesday. Chief Executive Donna Cooper said the attack disrupted some of its services but it had a plan in place and the bank remained sound.

Another bank, Westpac, said it successfully repelled an attack two weeks ago and hadn't been hit again since. News organizations Stuff and RNZ reported they had repelled attacks over the weekend.

The weather organisation MetService was also hit this week, switching its website to a stripped down version in order to stay online.

NZX said despite more attacks on its website, so far this week it has been able to trade uninterrupted.

"NZX has been advised by independent cyber specialists that the attacks last week are among the largest, most well-resourced and sophisticated they have ever seen in New Zealand," chief executive Mark Peterson said in a statement.

Little said the attacks were a wake-up call to all organisations with customer-facing websites. Only a few organisations seem to have been targeted at any one time and most have been able to repel the attacks, giving him confidence the country can move past them.