A Tokyo government website tasked with tackling child abuse unintentionally appeared to do the exact opposite when a caption under an image of a mascot skipped a vital word, government officials said Wednesday.

The homepage caption text under an image of the metropolitan government's official anti-child abuse snail mascot "Osekkai Kun" was meant to read "child abuse prevention promotion character," but instead read "child abuse promotion character."

(Erroneous caption shown bottom left on the website)[Supplied photo]

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The mistake was pointed out by a resident and fixed Tuesday, two months after the errant text was first placed on the site following its April 10 relaunch. An external contractor was outsourced for the project, according to the officials.

Before it was removed, the site drew ire on the internet, with people making comments such as "you shouldn't be promoting child abuse" and "it means the opposite."

"This is a mistake that should not have happened, especially from a standpoint of trying to prevent child abuse," an official from Tokyo's Bureau of Social Welfare and Public Health said.

"We will put all efforts into ensuring it doesn't happen again as we continue to raise awareness and educate people about abuse prevention," the official said.