Former Australian prime minister Malcolm Turnbull said Friday that retiring News Corp and Fox Corp chairman Rupert Murdoch had done "enormous damage" to the democratic world.

Turnbull, a renowned News Corp critic, said he expected the 92-year-old Australian-born media boss to remain "extremely influential" despite his announcement that he is stepping down as boss of the sprawling media group and handing over to his son Lachlan.

"He has done enormous damage to the democratic world and in particular the United States," said Turnbull, a former conservative Liberal Party prime minister who was ousted by hardline conservatives in a 2018 party coup supported by the Murdoch press.

Fox News had left the United States angry and divided, he said, alleging it had "knowingly spread lies", including about former president Donald Trump's loss in the 2020 US presidential election.

Murdoch's media had also been the loudest to "deny the reality of global warming and delay action to address it", Turnbull said in an interview with Australian public broadcaster ABC.

The former Australian leader said he had known Rupert Murdoch and his son Lachlan for a long time.

"I think Rupert has always been fascinated by power, that he's drawn to it like a moth is to a flame," Turnbull said.

"My impression is that Lachlan is more ideologically conservative than Rupert," he said.

"I don't think there is going to be any change for the better, that's for sure."