The lead independent director of Rupert Murdoch’s News Corp, Peter Barnes, says the media group’s board has yet to discuss James Murdoch’s attack on the company over its stance on the climate crisis.

On Wednesday James Murdoch, Rupert Murdoch’s son and a News Corp director, issued a joint statement with his wife, Kathryn Murdoch, in which the couple said they were frustrated by coverage of the climate crisis by Fox News and News Corp.

“They are particularly disappointed with the ongoing denial among the news outlets in Australia given obvious evidence to the contrary,” a spokesperson for the couple said.

James Murdoch’s intervention – a rare attack by a company director on his own group’s operations – added fuel to an already raging debate in Australia over News Corp’s coverage of global heating and the deadly bushfires that have devastated the country’s eastern seaboard.

Shareholder activists said the move added to the pressure on News Corp over the climate emergency and could lead to investor attacks on management at the company’s annual meeting later this year.

It also appears to reignite a succession battle between James Murdoch and his brother, Lachlan, that seemed resolved in 2018 when Lachlan was given important executive positions within the family empire as part of a restructure of the group.

News Corp itself battened down the hatches on Wednesday, with management in Sydney and New York declining to comment on the Murdoch scion’s comments.

The atmosphere inside the company’s Australian headquarters on Holt Street in Sydney was guarded on Wednesday as staff grappled with the unexpected attack, News Corp sources said.

However, Barnes, a former executive with tobacco company Philip Morris who now serves as the lead independent director on News Corp’s board, told the Guardian he was aware of media reports of James Murdoch’s statement.

As lead director, Barnes has an important role on the News Corp board that includes acting as a conduit between News Corp and investors, helping to set the pay of executives and acting as chair of the audit committee.

Speaking on Wednesday afternoon, Australian time, he said he had no comment on James Murdoch’s statement.

“What I’ve read in the papers is breaking news and we don’t meet again until the middle of February,” he said. “As you would no doubt know, this board has quite a lot of international people.”

In addition to James Murdoch, his brother, Lachlan Murdoch, and father, Rupert Murdoch, who is executive chairman, News Corp’s board includes the former president of Spain, José María Aznar, Ana Paula Pessoa, who is a director of Brazilian artificial intelligence company Kunumi, and former US senator Kelly Ayotte.

“I understand from the papers that James has made a statement but I have no comment to make because I haven’t made contact with them [the other directors],” Barnes said.

Brynn O’Brien, who heads the the Australasian Centre for Corporate Responsibility, said the shareholder activist group currently held no shares in News Corp.

“The pressure’s mounting on them on climate change, so let’s see,” she said. “It’s a very unusual situation where you have a board member on the record, through a spokesperson, attacking the governance and operations of the company.”

Shareholder activist Stephen Mayne, a former News Corp journalist who has repeatedly attacked the company over issues including a two-class share structure that cements the control of the Murdoch family, said an “obvious next step” would be to put up a resolution on climate change at the next AGM, which is likely to be held in October or November.

“I certainly think there’s a big opportunity for the full symphony of shareholder resolutions and engagement,” he said.

Spokesmen for News Corp in Sydney and New York declined to comment on James Murdoch’s comments.

The Sydney representative said the company stood by comments made by News Corp Australia chairman, Michael Miller, on Friday in response to a leaked email to him in which an employee accused News Corp papers, including the Australian, the Daily Telegraph and the Herald Sun, of spreading misinformation by focusing on arson as the cause of the bushfires, rather than climate change.

Miller said News Corp “does not deny climate change or the gravity of its threat”.

“Our coverage has recognised that Australia is having a serious conversation about climate change and how to respond to it,” he said. “However, it has also reflected there are a variety of views and opinions about the current fire crisis. The role of arsonists and policies that may have contributed to the spread of fire are, therefore, legitimate stories to report in the public interest.”

Even this week Telegraph columnists were still blogging about the “woke greenies” who were responsible for the fires and “the distorted debate.”

In his Monday Daily Telegraph blog, Tim Blair quoted Breitbart columnist James Delingpole: “Where this Australian bushfire tragedy is concerned, no one deserves more opprobrium than the greens whose poisonous, anti-human, anti-science, anti-history ideology has turned what could have been a minor inconvenience into a full-on disaster.”

He went on to link to Delingpole’s column, whose central thesis was that the fires had nothing to do with climate change.

“The dry, hot conditions which have exacerbated these fires are weather, not climate,” he writes. “Australia, a hot, dry country, has been here many, many times before.”

On Wednesday, columnist Miranda Devine stridently counselled Scott Morrison to resist a royal commission into the bushfires, arguing that “global forces are using Australia’s fires as propaganda to drum up support for their climate agenda”.

Measured by loss of life, Devine argues the 2009 Victorian fires were a far bigger tragedy. Victoria had a royal commission into those fires.

“Even if you accept the proposition that humans can dial down the earth’s temperature by not using fossil fuels or eating meat, Australia creates a puny 1.3% of the world’s carbon dioxide emissions,” she argued. “Morrison could capitulate to the carbonistas, and close down Australia, but it won’t stop the bushfires.

“Blaming climate change is a cynical diversion from the criminal negligence of governments which have tried to buy green votes by locking up vast tracts of land as national parks yet failed to spend the money to control ground fuel and maintain fire trails.”

A 2013 study of News Corp’s coverage of climate change found almost half its comment pieces expressed doubt about climate science. It has continued to publish climate deniers whose columns have been comprehensively debunked by scientists.