Burger King’s latest advert for its Whopper has backfired after the iconic burger’s Wikipedia page was manipulated to claim that the product contains “cyanide” and is "the worst hamburger product" the fast food chain has ever made.

On Wednesday, Burger King released a 15-second advert in the US which claimed there was not enough time to explain “all the fresh ingredient in its Whopper sandwich”.

Instead, an a Burger King staff member asks Google to do the explaining for him, using the voice prompt: “OK Google, what is the Whopper Burger?” after which the ad ends.

But the marketing stunt backfired after somebody altered the first line of the Wikipedia entry to say that the burger contains “cyanide” and is “cancer-causing”.

The entry also reportedly described the Whooper as "the worst hamburger product" sold by Burger King.

"Burger King saw an opportunity to do something exciting with the emerging technology of intelligent personal assistant devices,” a representative for the chain said on Wednesday.

Burger King, which is owned by Restaurant Brands International, also admitted the advert was not designed in collaboration with Google.

Reports suggested that Google's voice-activated Home smart speaker stopped responding within hours of the commercial’s release, implying that Google had updated the software to stop it from reacting to the specific Burger King advert.

Google did not reply to request for comment.

At the time of writing, the Wikipedia page, described the Whopper as “a hamburger sold by the international fast-food restaurant chain Burger King and its Australian franchise Hungry Jack's”.

It also described it “as the signature product of the company” which is “often at the centre of advertising promotions, product tie-ins, and even corporate practical jokes and hoaxes”.