A new program scans a face and then trawls the web for photographs of that person is to be made publicly available.
The software, which was developed by Israel-based Face.com, is thought to be correct 90 percent of the time and is already being used by 5,000 developers, although the reasons they were using the software was not disclosed.
It scans the position of a person's eyes, nose and mouth and then selects images on the web of faces with those features in the same positions.
Until now, similar software has only been available to government organisations such as the UK Border Agency or those developing social networks.
However, privacy campaigners including Simon Davies, director of Privacy International, have raised concerns over the software.
"I think this will make many people very uneasy. The regulators have been hugely behind the curve of protecting people's privacy on the internet. We need to push for much tighter international rules."
According to the Information Commissioner's Office there are currently no laws regarding the use of facial recognition software.
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