If you’re in the UK and access a website that offers pirated content, don’t be surprised to see a pop-up banner warning you that the site is under investigation and advising you to close the browser.

The intellectual property crime unit (PIPCU), run by the City of London Police, has started replacing paid-for ads on these copyright-infringing websites with such warning banners, in a bid to disrupt a source of revenue that these sites typically rely on.

The head of PIPCU, Andy Fyfe, says in a statement that this will also help consumers: “When adverts from well known brands appear on illegal websites, they lend them a look of legitimacy and inadvertently fool consumers into thinking the site is authentic.”

The police force worked together with ad-tech firm Project Sunblock to come up with such warning banners, as part of an initiative called Operation Creative that ties up with creative and advertising industries in the UK to prevent sites from feeding users illegal copyright-infringing content.

The sites that are being targeted have been reported to the police by rights holders who have to provide detailed evidence of how the site is involved in illegal copyright infringement, after which they will be evaluated and verified. The police will first contact the site owner to offer a chance to correct the behavior and choose to operate legitimately — if not, authorities will seek suspension of the site from the domain registrar or replace ads to disrupt revenue.

Headline image via Dan Kitwood/Getty Images