The chief executive of online bulletin board Reddit has admitted to changing posts by supporters of US President-elect Donald Trump on the website.

Steve "Spez" Huffman, also the site's founder, said in a post he redirected abusive posts targeted at him by users of Mr Trump fan community "The_Donald" to its moderators instead.

He said he "messed with" the posts for about an hour, and members of the community soon noticed their content had been changed without their consent.

"As the CEO, I shouldn't play such games, and it's all fixed now," he said.

"Our community team is pretty pissed at me, so I most assuredly won't do this again."

Mr Huffman said the abuse had been directed at him after Reddit moved to shut down subreddit community "Pizzagate", which was based on "fake news" allegations Democratic presidential candidate Hillary Clinton was kidnapping, molesting and trafficking children in the back room of a Washington pizza restaurant.

Now-banned subreddit community "Pizzagate" was based on "fake news" allegations about Hillary Clinton. ( Reuters: Brian Snyder )

The restaurant's owner and employees told The New York Times they received death threats and abusive messages as the accusations spread online.

The subreddit was banned and was replaced by a warning: "We don't want witch-hunts on our site."

Community members responded to Mr Huffman's post, with some calling for his resignation.

"That is a horrendous ethics violation for a CEO. Fire yourself," one user posted.

Another user wrote: "Surely editing others' comments is a bigger violation of Reddit TOS (terms of service) than whatever pizzagate is accused of doing."

Last year, Mr Huffman replaced interim chief executive Ellen Pao, who resigned after she provoked anger with the unexplained firing of an employee.