The creator of The Simpsons, Matt Groening, says Fox News threatened legal action after an episode poked fun at the channel.

The episode featured a "Fox News Crawl" at the bottom of the screen. It read: "Pointless news crawls up 37 per cent ... Do Democrats cause cancer? Find out at foxnews.com ... Rupert Murdoch: Terrific dancer ... Dow down 5000 points ... Study: 92 per cent of Democrats are gay ... JFK posthumously joins Republican Party ... Oil slicks found to keep seals young, supple ..."

Groening told National Public Radio that, after the episode was broadcast on Fox, he was threatened with legal action by the news channel.

"We did the crawl along the bottom of the screen [and] Fox said they would sue the show," he said. "We called their bluff because we didn't think Rupert Murdoch would pay for Fox to sue itself. We got away with it.

"But now Fox has a new rule that we can't do those little fake news crawls on the bottom of the screen in a cartoon because it might confuse the viewers into thinking it's real news."

Robert Zimmerman, a spokesman for Fox News Channel, denied they had threatened to sue the show. "We are scratching our heads over here. We liked the cartoon. We thought it was great," he said.