A massive cyber-attack using tools believed to have been stolen from the US National Security Agency (NSA) has struck organisations around the world.
Cyber-security firm Avast said it had seen 75,000 cases of the ransomware – known as WannaCry and variants of that name – around the world.
There are reports of infections in 99 countries, including Russia and China.
Among the worst hit was the National Health Service (NHS) in England and Scotland.
The BBC understands about 40 NHS organisations and some medical practices were hit, with operations and appointments cancelled.
The malware spread quickly on Friday, with medical staff in the UK reportedly seeing computers go down “one by one”.