Some global brand names are unknowingly advertising on pornography and extremist websites, including those of Islamic terror groups and white supremacists, generating tens of thousands of pounds a month for the owners.

An investigation by The Times revealed that large companies, universities and charities have had their advertisements appear on hate sites and YouTube videos created by supporters of terrorist groups such as Islamic State and Combat 18, a violent pro-Nazi faction.

The list of companies includes Mercedes-Benz, Waitrose, Marie Curie, Sandals Resorts, Honda, Thomson Reuters, Halifax, the Victoria & Albert Museum, Liverpool University, Argos, and Churchill Retirement.

Ads for John Lewis, Dropbox and Disney are embedded in sunnah-online.com, which hosts lectures of banned preacher Abu Ameenah Bilal Philips and terrorist Esa al-Hindi.

Lloyds Bank is promoted on eramuslim.com, a site which the Indonesian government banned in January 2017 for allegedly promoting hate speech.

An ad appearing alongside a YouTube video puts an average of $7.60 (£6.24) for every 1,000 views in the pocket of the person who posted the video. Some more popular extremist videos have recorded over one million hits.

The Times reported that leaked documents from one of the top six advertising agency revealed about 40% of its advert-buying income in 2015 was derived from hidden kickbacks as well as from "other income," which a source said came mainly from mark-ups applied to digital commercials.

The newspaper says that blacklists designed to stop advertisements from appearing next to online extremist content "are not fit for purpose." As an example, it cited the case of the ad for the new Mercedes E-Class saloon which appears on a pro-Isis video. The video had 115,000 hits. Similarly, luxury holiday operator Sandals Resorts is seen advertised along a video promoting al-Shabaab, the East African jihadist group affiliated to al-Qaeda.

A Sandals spokeswoman insisted that "every effort" was made to stop its adverts appearing next to inappropriate content and that YouTube had "not properly categorised the video" in question as sensitive.

It also noted that several companies admitted they were not aware that their ads were being placed on offending sites and blamed it on programmatic advertising — a computerised system of buying advertising space on webpages in the moments that they load up.

Several advertising agencies have their own programmatic divisions, which often apply mark-ups to digital commercials without the brands' knowledge.

YouTube took down some of the offending videos after being alerted by the newspaper. A spokesperson for Google in an email to IBTimes UK said: "When it comes to content on YouTube, we remove flagged videos that break our rules and have a zero tolerance policy for content that incites violence or hatred."

"Some content on YouTube may be controversial and offensive, which is why we only allow advertising against videos that fall within our advertising guidelines. Our partners can also choose not to appear against content they consider inappropriate."

The Times noted that the six top advertising agencies have each denied any wrongdoing or conflict of interest and that their relationships with their clients were transparent.