However, he said that so far "remarkably" few payments had been made by victims of the attack.
"At the moment we are in the face of an escalating threat, the numbers are going up".
The impact of Friday's worldwide cyber attack is feared to continue to have an impact today, as workers switch on their computers for the first time since before the weekend.
The ransomeware spread to 150 countries, including Spain, Russia, and the United States.
Meanwhile, HSE chief Tony O'Brien urged caution. However, that number may grow in the days ahead.
Last night, Broadway Medical Centre in Fleetwood cancelled all routine appointments today, but said it would still operate its same day/triage system for urgent queries and appointments.
"Right now, just about every IT department has been working all weekend rolling this out", said Dan Wire, spokesman at Fireeye Security.
Professor Helen Stokes-Lampard of the Royal College of General Practitioners said many Global Positioning System went into their practices on Sunday to reboot their computers and install updates.
Acting President, Yemi Osinbajo fails to inagurate ministers
The Presidency on Wednesday said the 2017 Appropriation Bill passed into law week is yet to be transmitted to it by the National Assembly.
A spokesman advised patients to continue to use the NHS "wisely" while IT technicians work to resolve the problem.
The ransomware called Wanna Decrypt, also known as WannaCry, encrypts files on the machine, effectively locking them.
Ryan Kalember, senior vice president at Proofpoint Inc., which helped stop its spread, said the version without a kill switch could spread.
Activity has been partially interrupted on Saturday at the Dacia plants of Mioveni, following a cyberattack that affected some of the information systems, according to a company release sent on Saturday.
"We have been concerned for some time".
Pic: ReutersWASHINGTON/FRANKFURT: Officials across the globe scrambled over the weekend to catch the culprits behind a massive ransomware worm that disrupted operations at vehicle factories, hospitals, shops and schools, while Microsoft on Sunday pinned blame on the US government for not disclosing more software vulnerabilities. "They are processing a lot of sensitive data", said Mr Wainwright.
"On Monday morning at the start of the new working week, it's likely that successful attacks from Friday that haven't yet become apparent will become apparent", he said.
Microsoft released patches last month and on Friday to fix a vulnerability that allowed the worm to spread across networks, a rare and powerful feature that caused infections to surge on Friday.
Capitalising on spying tools believed to have been developed by the US National Security Agency, the virus dubbed WannaCry has blocked more than 200,000 computers across the globe, demanding a ransom to unlock them.