London [U.K.], May 13: The cyber attack that hit the National Health Service (NHS) England is part of a wider worldwide attack, British Prime Minister Theresa May has said.
All told, several cyber security firms said they had identified the malicious software, which so far has been responsible for tens of thousands of attacks, in more than 60 countries.
The National Cyber Security Centre applauded his actions and said in a statement: "Media reports today have rightly praised the efforts of MalwareTech to tackle the Wannacry cyber attack".
French carmaker Renault's assembly plant in Slovenia halted production after it was targeted.
Nissan's plant in Sunderland has been affected by the global ransomware attack that has also affected the NHS and the French vehicle maker Renault.
There are warnings, however, that the attackers could tweak the code behind the chaos and start the cycle again.
The spread of the ransomware capped a week of cyber turmoil in Europe that began the previous week when hackers posted a trove of campaign documents tied to French candidate Emmanuel Macron just before a run-off vote in which he was elected president of France.
Health workers reported being locked out of their systems and seeing messages demanding ransom payments to regain access.
In a statement, global shipper FedEx said it has been badly hit by the cyber attack.
Britain's home secretary says about one in five National Health Service trusts have been hit by the global ransomware cyberattack, and that all but six are now back to normal.
Megafon, a Russian telecommunications company, was also hit by the attack.
Barts officials had to cancel routine appointments and divert ambulances to neighboring hospitals, they said, adding that the switchboard at Newham University Hospital also was affected.
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Chris Wysopal, of the software security firm Veracode, said criminal organisations were probably behind the attack, given how quickly the malware spread.
"I believe many companies have not yet noticed", said William Saito, a cyber security adviser to Japan's government.
"We are continuing to take the appropriate steps to address the situation".
Ms Rudd said Health Secretary Jeremy Hunt had told health trusts to upgrade their software and a lot of them had.
The head of Slovenia's cyber emergency team, Gorazd Bozic, says seven individuals have also been targeted but no state institutions.
That exploit was one of many hacking tools stolen from the NSA and published online by a group that called itself the Shadow Brokers on April 14, according to Avast.
Cyber-security firm Avast said it had seen 75,000 cases of the ransomware - known as WannaCry and variants of that name - infect computers internationally.
Although Microsoft released a security patch for the flaw earlier this year, many systems have yet to be updated, researchers said.
He said the affected computers likely had not applied the Microsoft patch or were running old operating systems for which no patch was available.
Microsoft on Friday said it was pushing out automatic Windows updates to defend clients from WannaCry.
Britain's National Cyber Security Center and its National Crime Agency were looking into the United Kingdom incidents, which disrupted care at National Health Service facilities.
She added: "Where the patient data has been properly backed up, which has been in most cases, work can continue as normal because the patient data can be downloaded and people can continue with their work". The interior ministry said on its website that around 1,000 computers had been infected but it had localized the virus.