Europol Director Rob Wainwright told ITV's Peston on Sunday programme that the attack was indiscriminate.
Seven hospitals were still unable to accept emergency patients two days after a global cyber attack brought down dozens of NHS systems.
An Garda Síochána said early Sunday there had been no identified cyber attack on any Irish state computer system from the wave of global ransomware attacks, although RTÉ reported a suspected attack on healthcare facility in the south-east.
Mr Wainwright said the attack was indiscriminate, fast-spreading and unique because the ransomware was being used in combination with a worm which means the infection of one computer could automatically spread it through a whole network. While most of the targets were located in Russia, Ukraine, and Taiwan, other victims have been identified in Europe. They became aware of it when we had the incident with the Census, so there are no excuses.
Spokesman Jan Op Gen Oorth said Sunday that the number of individuals who have fallen victim to the cyberextortion attack could be much higher.
Cyber security experts have warned that the ransomware virus, that affected one in five NHS Trusts last week, could be reactivated by computers and devices that have not yet been switched on.
By registering the domain, the researcher activated a kill switch that aborted the ransomware's execution routine, effectively defanging WannaCry.
The leaked hacking tools publicized a vulnerability in Windows, Microsoft's ubiquitous computer operating system. While this particular ransomware was inadvertently stopped, hackers could modify the code and try again.
WanaCryptor 2.0 is only part of the problem.
His move may have saved governments and companies millions of dollars and slowed the outbreak before USA -based computers were more widely infected.
The latest malware, called WannaCrypt or WannaCry, is spread by taking advantage of a Windows vulnerability that Microsoft released a security patch for in March.
Germany's rail operator Deutsche Bahn said its station display panels were affected.
Users that want to protect their computers from WannaCry attacks need to install security updates released by Microsoft.
Officials across the globe are scrambling to catch the culprits behind a massive ransomware worm that disrupted operations at auto factories, hospitals, shops and schools, while Microsoft pinned blame on the United States government for not disclosing more software vulnerabilities.
People are reflected in a glass sign of a Telefonica building in Madrid, Spain, May 13, 2017.
The ransomware is a type of malicious software that infects a computer and restricts users' access to it until a ransom is paid to unlock it. As such, security, in some types of computing, is a commodity. The firm said it had warned about the exponential growth of ransomware, or crimeware, as well as the dangers of sophisticated surveillance tools used by governments.
FedEx: The company said it was "experiencing interference with some of our Windows-based systems caused by malware" and was trying to fix the problems as quickly as possible.
Dr Krishna Chinthapalli said the havoc wreaked on some health services in an worldwide cyber attack could encourage hackers to target hospitals.
The UK government called a meeting of its crisis response committee, known as Cobra, to discuss how to handle the situation.
UK Home Secretary Amber Rudd said on Saturday that, all but six NHS trusts' systems had been restored.