Describing it as "another serious ransomware attack," Europol said "critical infrastructure and business systems" were being targeted "with a new wave of ransomware, which is an updated version of Petya."
"The attack has caused infections worldwide and has not yet been stopped," the agency based in The Hague warned Wednesday.
Although director Rob Wainwright said the number of victims was not yet known, Europol has already set up a coordination cell and is "actively monitoring" the spread of the attacks.
"There are clear similarities with the WannaCry attack, but also indications of a more sophisticated attack capability, intended to exploit a range of vulnerabilities," Wainwright said in a statement.
Petya has been around since 2016, but it does not just encrypt files on infected devices it also overwrites the master boot record.
This has the effect of rendering the computer useless and prevents users from recovering any information, Europol said.
It warned that unlike WannaCry "this attack does not include any type of 'kill switch'."
"It is a demonstration of how cybercrime evolves at scale and, once again, a reminder to business of the importance of taking responsible cyber security measures," added Wainwright.
The malware, which first surfaced on Tuesday in Ukraine, locks away a computer's data and tells users they must pay to get is all back.
The European police agency urged anyone falling victim to the latest attacks not to pay up, but to report the incident to the police and to isolate and disconnect infected computers from the internet.
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