More than 5,000 websites have been hacked to force visitors' computers to run software that mines a cryptocurrency similar to Bitcoin.
Users loading the websites of the Information Commissioner's Office, the Student Loans Company, as well as the council websites for Manchester City, Camden, and Croydon - and even the homepage of the United States Courts - had their computers' processing power hijacked by hackers.
Malicious code for software known as "Coinhive", a program advertising itself as "A Crypto Miner for your Website" would start running in the background until the webpage is closed.
Security researcher Scott Helme was alerted to the hack by a friend who sent him antivirus software warnings received after visiting a UK Government website.
