People could be watched in their own homes or at work with hackers targeting household webcams and uploading live footage to the internet, the UK's privacy watchdog has warned.
The Information Commissioner's Office (ICO) has urged people to upgrade their passwords after a Russian-based website was found to be accessing cameras in everything from CCTV to baby monitors.
The website is thought to feature live feeds from homes and businesses across the UK, including a gym in Manchester, a bedroom in Birmingham, and an office in Leicester.
Simon Rice, ICO group manager for technology, said:
This is a threat that all of us need to be aware of and be taking action to protect against. Remember, if you can access your video footage over the internet, then what is stopping someone else from doing the same?
How to ensure your webcam is safe
First secure your router by changing the default administrator password
Ensure the router is using WPA2 encryption
Switch off SSID so that the name of your router is not broadcast to anyone within range
Change the default password for any other devices you use - baby monitors, webcams, printers
Ensure your mobile devices are fully protected with security software
Create strong passwords by using more than three words, different case letters, a symbol and a number
Avoid using information relating to family members or pets, favourite sports teams or personal information as a password
ITV News Consumer Editor Chris Choi reports on hackers invading peoples' privacy.
Many people use webcams to monitor their homes remotely while they are away - such as to keep an eye on pets - and view the footage over the internet.
There are 584 UK feeds on the website, showing still images stolen from private CCTV and refreshed on a regular basis, sitting alongside thousands more from systems across the world.
The website said what it does is "fully legal" and adds:
This site has been designed in order to show the importance of the security settings.
UK links on the site show images including:
Two unmade children's beds with pink bedding clearly visible in a home in Birmingham
A side-on view of a child's bed in Bedford
Infants' cots in bedrooms in London, Reading, Sheffield, Guildford and Hemel Hempstead
Living rooms in places including London, Kent, Essex, South Yorkshire, Brighton, Cambridge and Wales and Scotland
A small boy watching television in Woking, Surrey
A pile of post inside the front door of a home, suggesting the owners are away on holiday and potentially giving burglars a reason to target it.