Newly released court documents reveal that Rupert Murdoch, the billionaire owner of Fox News, acknowledged under oath that several Fox News hosts endorsed Donald Trump’s lie that the 2020 election was stolen from him.

The mogul made the admission during a deposition in the $1.6bn defamation lawsuit brought against the network by the voting machine company Dominion Voting Systems, which has accused Fox News and its parent company, Fox Corporation, of maligning its reputation. In his deposition, Murdoch said that the hosts Maria Bartiromo, Lou Dobbs, Sean Hannity and Jeanine Pirro “endorsed” the false narrative promoted by Trump.

“I would have liked us to be stronger in denouncing it in hindsight,” Murdoch said in the deposition, the New York Times reported on Monday.

In previous court filings, attorneys for Dominion have argued that Fox News hosts ridiculed Trump’s false claims of a “stolen election” while promoting those lies on television. While Sean Hannity pushed that narrative on his prime-time show, he allegedly wrote that Trump was “acting like an insane person”.

Even Murdoch himself dismissed Trump’s claims, describing the former president’s obsession with proving the election was stolen as “terrible stuff damaging everybody”.

Murdoch acknowledged in his deposition that he could have ordered the network not to platform Trump lawyers such as Sidney Powell and Rudy Giuliani on its programs: “I could have. But I didn’t,” he said.

Dominion’s defamation case is being described as a “landmark”. A Harvard law professor recently told the Guardian he had “never seen a defamation case with such overwhelming proof that the defendant admitted in writing that it was making up fake information in order to increase its viewership and its revenues”.

The Fox hosts were also privately critical of members of Trump’s team, including Sidney Powell, an attorney who claimed that Dominion’s machines had changed votes cast for Trump to Joe Biden. In a deposition, Hannity said: “That whole narrative that Sidney was pushing, I did not believe it for one second”.

Still, the network continued to give coverage to proponents of the election fraud narrative as it feared upsetting its viewers. In a conversation about the network’s coverage of the issue on 5 January 2020 – a day before rioters stormed the US Capitol in an attempt to stop the election from being certified – Suzanne Scott, the Fox News media chief executive, and Murdoch debated whether Fox hosts should acknowledge Trump’s defeat and admit that Biden won. “We need to be careful about using the shows and pissing off the viewers,” Scott told Murdoch.

Dominion sued Fox News and parent company Fox Corporation in March 2021 and November 2021 in Delaware superior court, alleging the cable TV network amplified false claims that Dominion voting machines were used to rig the 2020 election against Trump, a Republican who lost to Democratic rival Biden. Dominion’s motion for summary judgment was replete with emails and statements in which Murdoch and other top Fox executives say the claims made about Dominion on air were false – part of the voting machine company’s effort to prove the network either knew the statements it aired were false or recklessly disregarded their accuracy.

In its own filing made public on Monday, Fox argued that its coverage of statements by Trump and his lawyers were inherently newsworthy and that Dominion’s “extreme” interpretation of defamation law would “stop the media in its tracks”.

Reuters reported that a Fox spokesperson said that Dominion’s view of defamation law “would prevent journalists from basic reporting”.

A trial is scheduled to begin in mid-April.

Reuters contributed reporting