An example of a banner that will appear on a site suspected of copyright infringement.

The ads will advise users the website is under investigation from the City of London Police Intellectual Property Crime Unit (PIPCU) and advise them to leave the website.

The banners were created in-house by PIPCU’s corporate communications team.

PIPCU has partnered with Project Sunblock, which is offering its content verification technology for free to switch ads that were due to appear on the police unit’s list of infringing websites – which was made available to advertisers in March this year – to the police warning. Neither PIPCU or Project Sunblock will pay the websites for the warnings to appear.

Many marketers may not know their adverts are appearing on such sites as they employ the use of third party advertising networks, meaning it may not be clear until after an ad was served that it appeared on a questionable website.

Several such sites which have been blocked by internet service providers also employ the use of masked URLs, meaning even blacklists can be circumvented – including PIPCU’s infringing website list.

Duncan Trigg, CEO of Project Sunblock, told Marketing Week: “This is not just about the revenue ads provide these sites but in the eyes on the user a big brand can legitimise that content on the site.”

It will be difficult to estimate how much revenue might be disrupted by the latest stage of PIPCU’s Operation Creative, which aims to tackle intellectual property crime, disrupt criminals profiteering from piracy and protect the creative industries.

DCI Andy Fyfe, head of PIPCU, told Marketing Week Operation Creative is a “multi-phase” programme and that while some sites suspected of piracy have voluntarily ceased and desisted, the next stage could include “proper enforcement options”.

He added: “We may look to engage with colleagues in foreign jurisdictions. We are not thinking for one minute it’s going to be straightforward, but major websites have been taken down by law enforcement in the past.

“[But currently] we think the restriction of revenue will be a more effective way of dealing with them without the need to try to pursue [the matter] in the courts.”

Starting from next year, individuals in the UK who persistently download content illegally will receive up to four warnings a year following the country’s biggest internet service providers signing up to a voluntary copyright alert programme brokered by the government. However, if they choose to ignore the warnings, no further enforcement action will be taken.