It said its hospitals had shut down all computer systems as a protective measure and canceled all non-urgent activity.
The virus, which took control of users' files, spread to 100 countries, including India, the UK, Spain, France and Russian Federation.
And he cautioned against paying the ransom before exploring opportunities to regain access to the compromised data with authorities.
The political fallout from the attack escalated over the weekend as both Labour and the Lib Dems blamed the crisis in the health service on the government's failure to upgrade hospital computers.
Security experts tempered the alarm bells by saying that widespread attacks are tough to pull off.
Mr Wainwright said Europol was working with the Federal Bureau of Investigation to track down those responsible and said it was likely more than one person was behind the attack.
Ministers are to convene an extraordinary meeting of the National Cyber Resilience leaders' board on Tuesday to review the response to the breach.
Question 2: There have been at least 99 countries affected by it including United Kingdom and USA, but it isn't reported in India so far! The statement said antivirus systems are working to destroy it.
At this stage we do not have any evidence that patient data has been accessed.
"Patients who have appointments booked for Monday and beyond should attend as planned".
Australian officials said so far only three small-to-medium sized businesses had reported being locked out of their systems while New Zealand's ministry of business said a small number of unconfirmed incidents were being investigated. Many public computers still have Windows XP installed, and they could be susceptible to the malware if IT administrators have not downloaded the appropriate security patches.
"I don't think it's to do with that preparedness".
"The recent attack is at an unprecedented level and will require a complex global investigation to identify the culprits", said Europol, Europe's policing agency.
Mr Wainwright said the attack was "unprecedented in its scale" and warned many more people could find themselves affected.
Other reports put that number as high as 200,000.
Answer: It's too early to say who was behind this, ransomware is usually associated with highly organised criminal gangs.
The malware attack first emerged on Friday night but there were concerns of more disruption as workers switch on their computers this morning.
NHS Merseyside, which operates several hospitals in northwest England, tweeted that "following a suspected national cyberattack, we are taking all precautionary measures possible to protect our local NHS systems and services".
Major global companies said they also came under attack.
"We have stopped this one, but there will be another one coming and it will not be stoppable by us", the 22-year-old said.