Newshub staff have expressed shock at learning the media company is to close its newsroom operations from 30 June.

Newshub is owned by the global entertainment giant Warner Bros Discovery which also owns Eden, Rush, HGTV and Bravo.

Staff were called to a meeting at Newshub at 11am on Wednesday where they were told Warner Brothers discovery was starting consultation on a restructuring of its free-to-air business.

A statement issued by Warner Bros Discovery says it has "commenced consultation on a proposed remodelling and restructure of its ANZ free-to-air business in New Zealand".

Its Asia Pacific president James Gibbons says the move was a result of negative events in New Zealand and globally and "the impacts of the economic downturn had been severe".

The proposed new model would focus on a digitally led business with ThreeNow at its core, he says.

Warner Bros Discovery ANZ senior vice president head of networks Glen Kyne says the company had to keep looking at ways of reducing costs.

"We've now reached a stage where any further reduction in costs means proposing major changes. This is why we are proposing to shut down the newsroom.

"This would mean stopping all news production including the Newshub website from June 30," he says in the statement.

Newshub presenter Mike McRoberts tells RNZ the news was "heartbreaking".

He did not know what it meant for news but says: "We're a pretty good newsroom. If we can't make it work, who can?"

Newshub's Wellington bureau chief Caitlin Cherry took to LinkedIn following the announcement:

"So the news is out that there's a proposal to close Newshub at the end of June. It's very sad and there are a lot of pretty devastated staff.

"So I will be back in the market for work! Media, communications, digital, social media and management."

A Newshub staff member described the atmosphere in the meeting as "pretty grim".

"I think everybody's just trying to take it a step at a time," he says.

Another says it was a huge shock and everyone was incredibly upset.

Another staffer says it was unexpected.

"Mainly shocking just, I don't think anyone expected, really, for that to happen so suddenly.

"Some people here were upset because a few of them have been working here for 30 years."

It is understood about 200 staff are affected.

Newsroom founder Mark Jennings who was a former Newshub News Chief and was TV3's South Island bureau chief when the network began in 1989 told Nine to Noon he was deeply shocked by the announcement.

He says he would have expected a cut-back and trimming of shows, but not on this scale.

Mark says he expected all Newshub shows to go, including AM Show and Patrick Gower's show.

It would be a major blow for media diversity in New Zealand and in the past Newshub's newsroom had been "a very strong and vibrant player in the market", he says.

Warner Bros Discovery did not have a strategy for Newshub which was "really disappointing" and he understood Newshub had lost $100 million in the last three years, Mark says.

The changes would not just impact the news but the local production sector, he says.

Mark says Media and Communications Minister Melissa Lee now faced some serious questions.

"I wonder if it had been a New Zealand owner, whether the government might've taken a different view around this, but I guess because it's owned by a huge American, multi-national conglomerate, they would've been reluctant to intervene in any way."

Mediawatch's Colin Peacock says he expected channels like Three to keep running, but effectively without a news operation.

"We're talking about people who have been part of the landscape from the legacy of TV3, which stretches back more than 30 years.

"So people like Mike McRoberts for example, Samantha Hayes, familiar names in news, their whole Gallery press team, political editor Jenna Lynch.

"This is huge, particularly when you think of reporting important areas, like the economy, politics, and so on, for the hundreds of thousands that still get their news via television that I guess leaves TVNZ as practically the only game in town on TV."

- RNZ