Matua Marlborough will become Treasury Wine Estate's only winery in the country, after the company announced it was closing its Auckland operation.

Close to 50 people will be out of a job when Australian-owned Treasury Wine Estates closes its Auckland winery and moves all production to Marlborough.

The company made the announcement on Thursday, stating it was also closing the Matua packaging and cellar door site in Waimauku.

Treasury Wine Estates produces wine in New Zealand under four brands - Matua, Secret Stone, Angle Cove and Squealing Pig.

A company spokesman said about 50 people worked at their Auckland site and the "majority of those roles will be impacted". A handful of staff may be relocated to the company's Parnell sales office.

Last year, Treasury Wine Estates announced it would axe about 175 jobs across the organisation globally to cut costs by $35 million, as they wanted to invest more in consumer marketing.

Thursday's announcement was in addition to this, the spokesman said.

At this stage, the company would not be increasing their staff count in Marlborough, he said.

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The decision to close the Auckland winery was not an easy one, but it made sense as the majority of their grapes were sourced from Marlborough, he said.

"It was a difficult decision for us to make, especially considering the roles in Auckland, but we are trying to drive growth and investment and this is the best way."

Since taking full ownership of the Marlborough site in November 2012, the company had increased its crush capacity from 15,000 to 25,000 tonnes, with the installation of 48 150,000 litre tanks. It also constructed a wastewater treatment facility to handle expansion.

Treasury Wine Estates chief supply officer Bob Spooner said the multi-million dollar expansion of the Matua Marlborough winery meant it was capable of handling the increase in production.

"It makes sense to simplify and consolidate our production into one operation."

As well as closing its Auckland winery, the company will also close its Great Western winery in Australia. As a result, about 30 people were expected to lose their jobs.

However, the site will be maintained while it considers the operational future of the winery, which may include a potential sale, Spooner said.

"In Australia, the size and location of the Great Western winery means it is both under-utilised and increasingly non-viable as a production facility, so we are ceasing operations and moving production into other wineries in TWE's Australian wine production network in order to reduce costs and remove unnecessary complexity."

He admitted the decision to close two wineries would mean a significant change for the company's Australian and New Zealand wine production, and would impact "a number of roles", he said.

The changes would not impact any of Treasury Wine Estates brands or existing supply contract arrangements with grape growers, Spooner said.

The spokesman said the Auckland winery would be closed by March next year.

"It was a tough decision to make and personally I'm sad to see Matua Auckland close its doors."

Grapes from the Hawke's Bay and Gisborne would be processed by a third party, before being transported to Marlborough for the winemaking process, he said.