Tauranga Hospital put itself in self-imposed isolation from the internet over the weekend, due to a cyber security threat.

A global ransomware attack, which infected more than 230,000 computers across 150 countries in the past few days, was deemed too much of a risk to hospital computers for them to remain online.

BOPDHB information management general manager Owen Wallace says they took a number of steps to protect themselves.

'As part of that process the DHB did reduce access to the internet, including turning off web browsing and external email access for a period from Saturday night through to mid-afternoon Sunday.

'This was a precautionary measure taken at a time where such action would least inconvenience the services of the DHB whilst enabling technical staff to focus on checking the status of system protections.”

He stresses there were no impacts on patient services as a result of this measure.

'Compared to the potential impact of a successful cyber security attack on health services, it was considered appropriate.

'This was reflected in similar actions being taken by a number of other DHBs across the country.”

The ransomware attack, known as ‘WannaCry', involves locking and encrypting a user's computer files, threatening to delete them unless a ‘ransom' is paid in bitcoins to the developers of the virus.

Such viruses can often be avoided by not opening suspicious emails, and by keeping operating systems such as Windows up to date.