A US company installed a new "tracking" software on websites of the UK government, Royal family and Manchester City football club among others to follow the internet activity of people without their knowledge, according to a media report.
The software was installed on scores of sites including those of the Ministry of Justice, the Food Standards Agency (FSA), the royal family, British charities, health organisations, Manchester City football club and seven universities.
Advertising-tracking software called canvas fingerprinting takes a "snapshot" of a person's computer, which allows it to monitor their web use, The Sunday Times reported.
It works even if internet users take steps to prevent being tracked, such as deleting cookies, according to researchers from Princeton University in America and University in Belgium who discovered the technology on more than 5,000 websites.
The software was installed by AddThis, one of the world's largest online tracking companies, earlier this year while providing other services for the websites, the report said.
The Virginia-based organisation said it was only testing a prototype for research purposes from February to mid-July. It had deleted the software from all websites and the information collected would be used only for "internal research".
However, Mike Rispoli, spokesman for Privacy International, was quoted as saying by the British daily that it was "deeply troubling" that "intrusive and secretive" tracking software had been added to government sites without anyone knowing.
Oxfam, which unwittingly had the tool added to its home page, said it was removing all AddThis software from its website to protect the charity's backers.
Online tracking is a multibillion-pound industry that collects people's browsing habits and sells them to advertisers and online marketing firms.
In the past "data-mining" companies have used cookies - individual files downloaded to a person's browser - to track users.
The FSA said: "We were not aware that our use of AddThis included canvas fingerprinting. We have arranged for this to be removed."
The Ministry of Justice said: "We removed this platform from our website as soon as we were informed of these issues.
