Australian Greens senator Sarah Hanson-Young will chair the Senate inquiry she asked for after Kevin Rudd's #MurdochRoyalCommission petition attracted more than half a million signatures.

Rudd and another former prime minister who signed the petition, Malcolm Turnbull would have the opportunity to speak frankly with the protection of parliamentary privilege, "important when you're talking about issues of power and influence," Hanson-Young told Guardian Australia.

Her motion in the Senate was not opposed by the government and passed without a vote. The environment and communications references committee will call for submissions immediately and is due to report by the end of November 2021.

Hanson-Young - who chairs the committee - said it was clear from the petition that Australians were "very concerned about the concentration of media ownership and the power and political influence of Murdoch.

"As a parliament, it was right that we acted on those concerns. The media landscape in Australia has been changing rapidly."

Media voices were being lost across the country and access to news and public interest journalism was vanishing altogether in some regions, with increased pressure faced by small and independent publishers bad for democracy.

"We need to ensure we have a strong and independent public interest news industry to support our democracy," she said.

Meanwhile, News Corp Australia was playing down the role of the inquiry into media diversity, one of "at least nine media inquiries" in which executive chairman Michael Miller said the company had participated in the past decade. "As always, we will continue to constructively engage in these important conversations," he said in a statement.

What will matter is the terms of reference of the inquiry, to which News' editors and commercial executives will be called, as well as independent and regional and rural editors. Previous inquiries have tended to focus on specific topics, such as the reform of media ownership laws. Major publishers sought successfully to enable their ownership of TV companies, aspirations frustrated when CBS bought Channel Ten - previously controlled by interests including Lachlan Murdoch - from the administrator.

Both Rudd and Turnbull have spoken out on the role the Murdoch-owned News mastheads have played in influencing political outcomes, and the subject was raised again this week, with Turnbull confronting both former Sky News host David Speers and the Australian's editor-at-large Paul Kelly live on TV.

He told Speers he should have the opportunity to "tell the truth about what it was like working in Sky News", and asked Kelly "how offensive, how biased, how destructive" it would have to be before he left.

Guardian Australia quoted Labor communications spokeswoman Michelle Rowland that there were "already a range of reports and recommendations designed to support the media sitting in minister Paul Fletcher's too-hard basket".

She said Labor "would not stand in the way of Australians concerned about the media having a chance to be heard". While the party did not back Kevin Rudd's royal commission call, his petition was presented to parliament by a Labor MP, Andrew Leigh.

The terms of reference for the Senate inquiry call for an examination of the 'state of media diversity, independence and reliability in Australia and the impact that this has on public interest journalism and democracy'.

It will examine the state of public interest journalism, the impact of Australia's media ownership laws on media concentration and the viability of media business models. It does not mention News Corp Australia or Rupert Murdoch specifically.

Peter Coleman