The most disruptive attacks were reported in Britain, where hospitals and clinics were forced to turn away patients after losing access to computers.
NHS services across England and Scotland have been hit by a large-scale cyber-attack.
NHS Digital, which runs the health service's IT systems, said it had identified the malware software known as WannaCry, also known as Wanna Decryptor, which appears to be requesting $300 from victims to decrypt their computers.
Details of patient records and appointment schedules, as well as internal phone lines and emails, have all been rendered inaccessible.
Reports indicate that as many as 40 offices connected to NHS were impacted, though according to The Guardian, the United Kingdom hasn't yet moved to confirm this figure. In an statement released around 11:30 a.m. ET, the system's digital office said, "This attack was not specifically targeted at the NHS and is affecting organizations from across a range of sectors".
Cybersecurity firm Avast said it has tracked more than 75,000 attacks in 99 countries.
Hospitals were a prime target, Manzoni said, because "they are very vulnerable to cyber attacks and ready to pay because they can not afford any shutdowns".
Pictures posted on social media showed screens of NHS computers with images demanding payment of 300 USA dollars worth of the online currency Bitcoin, threatening to delete files within seven days.
WannaCry is a form of "ransomware" that locks up the files on your computer and encrypts them in a way that you can not access them anymore. "IT companies maintaining hospital networks can also be found negligent or at least careless, as usually a properly maintained and duly updated system is immune to the vast majority of ransomware".
Volk added that ministry experts are now working to recover the system and do necessary security updates.
Russian Interior Ministry spokeswoman Irina Volk confirmed that there was a ransomware attack on its computers.
Reports in Russian Federation say the nation's top criminal investigation agency, the Investigative Committee, has also been targeted.
A huge extortion cyberattack hit dozens of nations Friday, holding computer data for ransom at hospitals, telecommunications firms and other companies.
The attack has locked computers and blocked access to patient files. Many canceled all routine procedures and asked patients not to come to the hospital unless it was an emergency.
The US Department of Homeland Security said late on Friday that it was aware of reports of the ransomware, was sharing information with domestic and foreign partners and was ready to lend technical support.
A statement from NHS Digital said: "A number of NHS organisations have reported to NHS Digital that they have been affected by a "ransomware" attack".
In a tweet, Europol Director Rob Wainwright said the cyberattack on British health care institutions "follows trend from USA of ransomware attacks on health care trusts".
"Looking at the trends, it was going to happen", he said.
Spain, meanwhile, took steps to protect critical infrastructure in response to the attack.
Barts Health NHS Trust in London said on its website it was "experiencing a major IT disruption and there are delays at all of our hospitals".
"Let's hope that the attack on the National Health Service in Britain is simply a matter of inconvenience, and that nobody is denied essential care", he said in an email to FierceHealthcare. It is available in at least 28 languages, including Bulgarian and Vietnamese, according to Avast, a Czech security company that is following the fast-moving attack. The cyberattack, he said, could cause a major backlog in referrals. It's important to avoid clicking on links or opening attachments in those messages, since they could unleash malware, Villasenor said.