It warned computer users to install and upgrade security software as a precaution.
Elsewhere in Europe, the attack hit Spain's Telefonica, a global broadband and telecommunications company, and knocked ticketing offline for Norway's IF Odd, a 132-year-old soccer club.
British health minister Jeremy Hunt said yesterday that it was "encouraging" that a predicted second spike of cyber attacks had not yet occurred, but the ransomware attack was a warning. Police Scotland are working with the National Crime Agency on the investigation. "The message is very clear, not just for organisations like the NHS (National Health Service) but for private individuals as well as businesses".
"As a result of the attack, we will be reviewing and further strengthening our system protection arrangements", the spokesperson said. And NHS Digital has said there is no evidence patient data has been compromised. The payment of a ransom, however, may be unnecessary when up-to-date backups are available.
Routine operations were cancelled across Scotland during the attack, with health boards urging only those who urgently required treatment to visit accident and emergency departments.
Jan Filochowski, who ran six trusts including Great Ormond Street children's hospital in London, said: "Most of the NHS IT system is out of date".
"I don't think I'm ever going back to the MalwareTech that everyone knew", he added.
GP practices in the North East, which were impacted by the "cyber attack" on the NHS, were unable to use their IT systems for five days between 12-17 May. Doctors' practices and pharmacies reported similar problems.
"In addition to protective real-time monitoring of national NHS IT services and systems, which were unaffected by this issue, we are supporting NHS organisations by undertaking cyber security testing and providing bespoke advice and action points".
But on Tuesday afternoon the trust confirmed the services would return to normal tomorrow morning.
"Small business owners should be pro-active about their cyber security in the wake of this ransomware campaign affecting computers around the world", Tehan said.