A cyber-attack that hit organisations worldwide including the UK’s National Health Service was “unprecedented”, Europe’s police agency says, according to BBC.
Europol also warned a “complex international investigation” was required “to identify the culprits”.
Ransomware encrypted data on at least 75,000 systems in 99 countries on Friday. Payments were demanded for access to be restored.
European countries, including Russia, were among the worst hit.
Although the spread of the malware – known as WannaCry and variants of that name – appears to have slowed, the threat is not yet over.
Europol said its cyber-crime team, EC3, was working closely with affected countries to “mitigate the threat and assist victims”.
In the UK, the head of the cyber security agency said experts were “working around the clock” to restore the systems of some 45 NHS organisations that were hit by the attack.
The attack left hospitals and doctors unable to access patient data, and led to the cancellation of operations and medical appointments.
Who else has been affected by the attack?
Some reports said Russia had seen more infections than any other single country. Domestic banks, the interior and health ministries, the state-owned Russian railway firm and the second-largest mobile phone network were all reported to have been hit.
Russia’s interior ministry said 1,000 of its computers had been infected but the virus was swiftly dealt with and no sensitive data was compromised.
In Spain, a number of large firms – including telecoms giant Telefonica, power firm Iberdrola and utility provider Gas Natural – were also struck, with reports that staff at the firms were told to turn off their computers.
People tweeted photos of affected computers including a local railway ticket machine in Germany and a university computer lab in Italy.
France’s carmaker Renault was forced to stop production at a number of sites.Portugal Telecom, the US delivery company FedEx and a local authority in Sweden were also affected.
China has not officially commented on any attacks it may have suffered, but comments on social media said a university computer lab had been compromised.
Coincidentally, finance ministers from the G7 group of leading industrial countries had been meeting on Friday to discuss the threat of cyber-attacks.
They pledged to work more closely on spotting vulnerabilities and assessing security measures.