Whanganui District Health Board has been targeted by hackers who infected its computers with a "ransomware" attack.

The virus, known as "Locky", has spread to hundreds of thousands of computers around the world since first appearing on Monday.

Ransomware attacks restrict people from accessing files on computers until a ransom is paid to the hacker.

Forbes reported Locky was transmitted to computers via a Word document and encrypts files stored on the computer's network until a ransom of Bitcoin is paid. Researchers told Forbes Locky was being sent out by Russia's biggest cyber-criminal gang.

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Whanganui District Health Board's information and communications technology manager Barry Morris said the threat from Locky had been contained and no ransom was paid to the hackers.

"No further activity [has been] seen within the last 24 hours."

"The WDHB runs up-to-date operating systems with antivirus and malware protection," he said.

"We are reviewing security procedures to strengthen existing controls."

Earlier this week, a Los Angeles hospital hit by ransomware was forced to pay off the hackers targeting its network.

The Guardian reported Hollywood Presbyterian Medical Center lost access to its computer systems since February 5 after hackers installed a virus that encrypted their computer files.

The hospital paid the hackers $17,000 in bitcoin to regain access to the files.

A PwC New Zealand survey of concerns held by chief executives showed a big growth in concern around cybersecurity and data security sector.