There have been more than 200,000 victims in 150 countries from an "unprecedented" global cyber attack over the weekend that brought down NHS services and hit companies such as O2 owner Telefonica, Nissan and Renault.
The chief of Europol Rob Wainwright revealed the latest estimates of how far the ransomware has spread on Sunday morning, speaking to ITV's Peston on Sunday show, adding that it had "never seen anything like it".
The international police agency boss warned that "all sectors are vulnerable" and should all take "absolutely seriously" the need to run updated systems.
But Wainwright cited the banking sector as an example of good practice, however.
"Very few banks in Europe, if any, have been affected by this and that's because they've learned through painful experience about being the number one target in cyber crime, the value of having a strategy in place. And I think the health sector and others should follow of some others to make sure they sit up and take notice of what is a huge strategic concern."
The former chair of the Treasury Select Committee Andrew Tyrie has consistently criticised UK banks for not doing enough to prevent attacks after a string of data breaches and recently warned the lines of accountability for cyber security in the financial sector were "too opaque".
Defence secretary Michael Fallon today insisted the government was investing enough in cyber security to protect the UK's healthcare system from attacks after claims it had cut crucial spending.
Meanwhile Wainwright warned the threat from the ransomware would likely escalate when people return to work on Monday morning.
"At the moment, we are in the face of an escalating threat. The numbers are going up, I am worried about how the numbers will continue to grow when people go to work and turn (on) their machines on Monday morning," he said, adding that many victims will be businesses "including large corporations".