The global malware attack has reached Australians, the government confirmed. "There's no assurance that even if the government reveals a vulnerability people are going to move quickly enough to make and apply the patch".
Hospitals across Britain found themselves without access to their computers or phone systems.
Dr Nicky Williams, the commissioning group's deputy clinical chairman, said: "I'd like to thank patients for their understanding at this hard time".
Britain's home secretary said one in five of 248 National Health Service groups had been hit.
The National Cyber Security Centre, an arm of the GCHQ, the British electronic surveillance agency, said it was investigating the attack.
It was not yet known who perpetrated the attacks.
"The difficulty is, of course, there are literally hundreds of instances of ransomware in Australia each week, so we're now seeking to confirm whether these are examples of the particular ransomware that has caused so much havoc for example in the United Kingdom", she told reporters in Cairns.
Hospitals and GP surgeries in England and Scotland were among at least 16 health service organisations hit by a ransomware attack, using malware called Wanna Decryptor - with reports potentially dozens more were affected.
It demands payment in three days or the price is doubled, and if none is received in seven days the files will be deleted, according to the screen message. This is not the serious stuff yet. The attack affected PCs using Microsoft's Windows operating system. That number is likely to go up, Gazeley said.
Most big firms are making strident efforts to ensure that attacks like these can not be repeated. There have also been a large number of other suspected attacks, notably in Germany, the Philippines, Russia, Turkey and Vietnam.
The police have also briefed the Ministry of Health as a precaution. Russia's health ministry said its attacks were "effectively repelled".
The virus exploits a vulnerability in Microsoft Windows software, first identified by the US National Security Agency.
The Shadow Brokers released Eternal Blue as part of a trove of hacking tools that they said belonged to the USA spy agency. We are working closely with them and are being guided by their expert knowledge in this field.
"I think these hackers have to recognize that these authorities will come after them with a vengeance", Gazeley said. We'll note that Kaspersky supports NPR and is a provider of security services for its IT systems.
On Saturday, a cyber security researcher told AFP he had accidentally discovered a "kill switch" that could prevent the spread of the ransomware.
The 22-year-old Britain-based researcher, identified online only as MalwareTech, explained Saturday how he registered a garbled domain name he spotted in the code.
"The software has actually stopped spreading across the world", he told CNN. The user is asked to pay a ransom to unlock the computer.
Stevenage's Lister Hospital is still experiencing "major computer problems" following Friday's cyber attack in which a virus was introduced onto IT systems at NHS trusts, businesses and other organisations across the United Kingdom and globally. Computers already affected will not be helped by the solution. It is therefore vital to invest more in cyber-security training for all staff working with sensitive information. The exploit was leaked last month as part of a trove of NSA spy tools.
Prior to the dump, Microsoft released a fix, or patch, for the issue, although computers that did not install the update, or could not due to the age of their software, would have been vulnerable to attack.
The attack was carried out yesterday, Friday May 12.