United Kingdom works to restore NHS systems, Renault halts production after global cyberattack

Researchers with security software maker Avast said they had observed 57,000 infections in 99 countries, with Russia, Ukraine and Taiwan the top targets.

"This is child's play, what happened".

"Affected machines have six hours to pay up and every few hours the ransom goes up", said Kurt Baumgartner, the principal security researcher at security firm Kaspersky Lab. "There's no barrier to do it tomorrow to 100 million computers".

Earlier on Friday, Spain's government warned that a large number of companies had been attacked by cyber criminals who infected computers with malicious software known as "ransomware" that locks up computers and demands ransoms to restore access.

Researchers believe that the same weakness of the Windows operating system was previously identified by the National Security Agency in the United States of America, and was then leaked on-line by a group that calls itself "the Shadow Brokers".

The ransomware's progress has been halted by the accidental discovery late Friday of a "kill switch" hidden within the code by a security researcher, said cybersecurity consultant David Kennedy, formerly of the US National Security Agency.

It's not the first time hackers have used the leaked NSA tools to infect computers. His $11 purchase of the name may have saved governments and companies around the world millions, slowing its spread before USA -based computers were more widely infected.

In the US, FedEx Corp reported that its Windows computers were "experiencing interference" from malware, but would not say if it had been hit by ransomware.

U.S. Treasury Secretary Steven Mnuchin, at a meeting of world leaders in Italy, said the attack was a reminder of the importance of cybersecurity.

"He actually probably saved lives by accident", Kennedy said, referring to the security researcher who discovered the kill switch. In most cases, they change the wallpaper of the computer and give specific instructions telling the user how to pay to recover their files. Microsoft says now it will make the fixes free for everyone.

Security experts said the attack appeared to be caused by a self-replicating piece of software that enters companies and organizations when employees click on email attachments, then spreads quickly internally from computer to computer when employees share documents and other files. Microsoft has released software patches for the security holes, although not everyone has installed those updates.

Krishna Chinthapalli, a doctor at Britain's National Hospital for Neurology & Neurosurgery who wrote a paper on cybersecurity for the British Medical Journal, said many British hospitals still use Windows XP software, introduced in 2001.

Some said the attacks highlighted the need for agencies like the NSA to disclose security flaws so they can be patched.

Spokesperson Irina Volk was quoted by the Interfax news agency Saturday as saying the problem had been "localised" and that no information was compromised. Russia's health ministry said its attacks were "effectively repelled".

Russian cellular phone operators Megafon and MTS were hit.

Six NHS trusts are yet to return to normal around 24 hours after an worldwide cyber attack struck computer systems across the globe.

Germany's national railway said Saturday that departure and arrival display screens at its stations were affected, but there was no impact on actual train services.

The attack also forced French carmaker Renault to halt its production at sites in France in an effort to stop the malware from spreading. Deutsche Bahn said it deployed extra staff to busy stations to provide customer information, and recommended that passengers check its website or app for information on their connections.

Ms Rudd said work was ongoing to identify the attackers, and that no patient data had been stolen.

Elsewhere in Europe, the attack hit Spain's Telefonica, a global broadband and telecommunications company, and knocked ticketing offline for Norway's IF Odd, a 132-year-old soccer club.