YouTube has once again been strongly criticised for running ads alongside videos peddling outlandish theories.

Adweek reports that an ad for the Toyota Corolla was recently run before a video denouncing tests and treatment for HIV. An ad for Mercedes, meanwhile, was run before a video entitled ‘The AIDS Myth Unraveled’ which claimed that the disease is not caused by HIV, which in itself was said to be not dangerous.

Other companies whose ads were associated with the same or similar material included website building platform Wix, mattress company Saatva and insurance company Lemonade.

How many last chances?

"This should not have happened and we apologise for the mistake," YouTube said in a statement to Adweek. "The flagged videos earned less than $100 in total over the last 60 days.

“We immediately removed ads on violating videos and credited advertisers. While our system and controls work as intended 99 percent of the time, there are a small number of instances where they do not and we are committed to closing that gap even further."

This new follows hot on the heels of similar controversies such as a horror movie trailer running alongside kids videos and ads for anti-gay organisations.

The latter involved a video ad by Alliance Defending Freedom, which is a legal firm with a terrible track record of attacking gay rights, running at times alongside LGBT content and on channels including BuzzFeed and PewDiePie.

Other ads were also spotted, including one by conservative commentator ASKDrBrown which cites the bible in arguing that homosexuality is a ‘sin’.