Another 20 journalists will lose their jobs at the ABC as the broadcaster restructures its eight capital-city newsrooms for digital and multi-platform journalism.

ABC management says the cuts are not to save money but are driven by the growth of web and mobile audiences and the decline in broadcast TV and radio audiences.

In the past two years the audience for ABC news on mobile and on the web has grown by 12% to almost five million a month, while the smartphone audience has grown by 30%, the broadcaster has said.

The director of news, analysis and investigations, Gaven Morris, announced 20 roles would be made redundant in the city newsrooms but there would be “no cut to job numbers” as “new senior editorial roles” would be introduced.

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It is expected the traditional television and radio journalists will be made redundant to make way for digital-first employees.

“As Australia’s major public broadcaster, the ABC is continuing to provide news on traditional platforms at the same time as developing our digital presence to be as accessible as possible for all Australians,” Morris said. “While our newsrooms do great work, the current structures do not fully support our people to meet modern audience needs.

“Reshaping our newsrooms involves challenges. Overall, it is anticipated around 20 positions would become redundant, and we know this would be painful. Against this, new senior editorial roles would be introduced to add to the expertise and skills in the newsroom. At the end of this process we anticipate having the same number of editorial employees.”

The cuts follow the ABC’s decision to halve current affairs radio programs The World Today and PM in 2018 to fund other projects in news, including specialist and investigative reporting.

Morris said the new newsroom structure would provide a “faster breaking-news service” across TV, radio, web and mobile.

The management and structure of the newsrooms will also be changed.

The last significant job cuts at the ABC were announced in March 2017 when the managing director, Michelle Guthrie, cut 200 jobs in the TV news, television and content divisions.

In 2016 the ABC slashed the Radio National staff ranks and schedule, losing more than a dozen staff and several programs.

On Monday, the Media, Entertainment and Arts Alliance said the majority of those being tapped for redundancy were senior, experienced journalists.

The journalists who produce and report for the main 7pm news bulletins are particularly affected. They will be put in a “pool” and chosen for redundancy according to their skills.

“Staff who are on the chopping block are local journalists dedicated to local storytelling,” the director of MEAA media, Katelin McInerney, said. “Despite assurances from management that local coverage will not suffer, it is difficult to understand how axing senior, experienced journalists out of state newsrooms is not going to have an impact.”

But Morris said the restructure is about equipping the newsroom for coverage that suits the way the audience is consuming news. The average audience for the 7pm bulletin is in their 60s and young people are consuming news on mobiles and around the clock.

“The end game for me here is about journalism,” Morris told Guardian Australia. “I am not always convinced the standard of reporting is always as strong as it could be.

“I don’t think people look to us as much as they once did to cover the day’s events because there are so many places they can get that type of news coverage from.

“We need to be providing a point of difference in the media by doing a stronger brand of journalism.”