Friday's global cyber-attack has affected more than 200,000 victims in 150 countries and regions, Europol chief Rob Wainwright said Sunday.
"Many of those victims will be businesses, including large corporations. The global reach is unprecedented," he said in an interview with Britain's ITV.
Wainwright said he was concerned that the numbers of those affected would continue to rise when people returned to work on Monday morning.
"We're in the face of an escalating threat, the numbers are going up," he said, adding that the current attack was unprecedented.
Wainwright told ITV that the world faced an escalating threat, and there was concern about the level of potential attacks on Monday morning.
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 virus took control of users' files, demanding payments. Russia and Britain were among the worst hit countries. Britain's official emergency committee, known as Cobra, met in London Saturday afternoon to discuss the cyber attack that has caused widespread disruption to the country's National Health Service (NHS).
Around 45 NHS organisations in England and Scotland, including hospitals, family doctor surgeries, and health services, were hit in the cyber attack which prevented doctors, nurses and staff from accessing vital patient information.
However, Wainwright said Europol was working on the basis that the cyber attack was carried out by criminals rather than terrorists, but noted that "remarkably few" payments had been made so far.
"Most people are not paying this, so there ain't a lot of money being made with this by criminal organisations so far," he said.
