NHS England sought to reassure patients, advising that A&E and other emergency services should still be used if needed.
He added: "Where we need to cancel planned appointments, we will be contacting patients directly to make them aware and we apologise for any inconvenience caused". The software took control of the people's computer and files and demanded users to pay $300 (Rs 19,000 approx) in virtual currency Bitcoin to unlock the files and regaining access to their systems.
Over the weekend, hundreds of thousands of computers around the world were hit by a large-scale ransomware attack.
The spokesman said that the National Cyber Security Centre in the Department of Communications, Climate Action and Environment is "monitoring the situation on an ongoing basis".
Dr Anne Rainsberry, NHS incident director, said: "We have been working with 47 organisations providing urgent and emergency care who have been infected to varying degrees".
Modi meets Palestine President
Abbas, on the other hand, condemned terrorism and said he has agreed with United States to end conflict with Israel. Abbas said Palestine appreciated the solidarity India extends to its cause.
Although there are fears that a new strain of the WannaCry virus could be used to deliver another coordinated attack, the bigger threat is likely to come from machines already infected from Friday's hack.
There have been calls in Britain for an inquiry into the circumstances surrounding Friday's major incident, with the United Kingdom government and NHS chiefs facing questions over their preparedness and the robustness of vital systems.
The malware is a type of ransomware that seems to have spread via a computer virus known as a worm, meaning that it can move throughout a network without human interaction.
In a statement Microsoft also fiercely criticized governments for stockpiling software vulnerabilities, instead of informing the software company of issues so that customers can be protected.
Microsoft released a security patch for the vulnerabilities in March.
Microsoft first introduced Windows XP in 2001 and stopped offering security updates and bug fixes several years ago.
Wainwright warned the healthcare sector "in many countries" was particularly vulnerable, but that all organizations should ensure they prioritise cyber security and update their systems.
The attacks affected 150 countries and infected at least 200,000 computers worldwide, despite global cyber security firms warning last month that they were expected.
Maria Sharapova through to second round in Rome
Sharapova won the next two games and although McHale broke back to make it 5-2, Sharapova took the next game to clinch victory. McHale seized on her opponent's wayward start and forged ahead against the serve when Sharapova sent a forehand long.
Hundreds reported killed in Libya airbase attack
Also on Friday, a auto bomb south of Benghazi killed a prominent tribal leader linked to the LNA along with five other people. The UN envoy to Libya earlier on Friday voiced alarm at reports of the attack on the base, 650 kilometres south of Tripoli .