The UK’s privacy regulator said it is studying the use of controversial facial recognition technology by property companies amid concerns that its use in CCTV systems at the King’s Cross development in central London may not be legal.

The Information Commissioner’s Office warned businesses using the surveillance technology that they needed to demonstrate its use was “strictly necessary and proportionate” and had a clear basis in law.

The data protection regulator added it was “currently looking at the use of facial recognition technology” by the private sector and warned it would “consider taking action where we find non-compliance with the law”.

On Monday, the owners of the King’s Cross site confirmed that facial recognition software was used around the 67-acre, 50-building site “in the interest of public safety and to ensure that everyone who visits has the best possible experience”.

It is one of the first landowners or property companies in Britain to acknowledge deploying the software, described by a human rights pressure group as “authoritarian”, partly because it captures images of people without their consent. Canary Wharf is also interested in deploying the technology.