A massive cyber attack on Friday affected 74 countries across Europe and Russia, disrupting Britain's health system and infecting dozens of other countries around the world, Reuters reports.
According to the news agency, the hackers used tools widely believed to have been developed by the U.S. National Security Agency (NSA).
Hospitals and doctors' surgeries in parts of England were forced to turn away patients and cancel appointments after they were infected with the ransomware, which scrambled data on computers and demanded payments of $300 to $600 to restore access.
People in affected areas were being advised to seek medical care only in emergencies.
Telecommunications giant Telefonica was among many targets in Spain, though it said the attack was limited to some computers on an internal network and had not affected clients or services.
Also targeted was top Russian mobile operator Megafon, according to The Associated Press.
Pyotr Lidov, a spokesman for Megafon, said the attacks froze computers in company offices across Russia. He said that mobile communications haven't been affected.
Some Russian media also reported cyberattacks on the Interior Ministry and the Investigative Committee. The committee, the nation's top investigative agency, has rejected the claim, according to AP. READ MORE