Finance Minister Grant Robertson said there were problems in the aluminium market. "As a sector, it has had its troubles." Rio Tinto was having discussions around the world with Governments.

Robertson said the position of the New Zealand Government had been the same as it had been since 2013.

"This is really not related to Covid-19, let's be frank about that." Rio Tinto had been attempting to sell the smelter since 2011. "This is a decision they've been looking at for many, many years."

Energy Minister Megan Woods said the smelter was receiving large subsidies under the emissions trading scheme while transmission pricing plans released recently would also have lowered the smelter's transmission costs.

"This is a blow for the people of Southland and I feel for them, but we need to look to the future," Robertson said.

Woods said there was "a clear understanding" that direct subsidies were not on the table. The smelter wanted a "prudent discount" on transmission pricing. However a formal application had not been put in.

Robertson said the Government was informed of the decision just prior to the news being released publicly. He repeated that there was a degree of inevitability to the news.

"We'll always keep lines of communication open," Robertson said, however the statement appeared to be "definative".

Woods said it was "pretty inevitable" that companies would signal that they would put investment plans on hold. "This won't come as a surprise, it was a matter of when, not if." She said a number of wind projects were underway.

Woods said it was the Government's expectation that the site would be cleaned up, which is expected to cost around a quarter of a billion dollars.

• Rio Tinto announces plans to close smelter, more than 1000 jobs on the line

NZ First MP Mark Patterson said Rio Tinto was "playing games" with the people of Southland.

"It is unconscionable that despite massive support from New Zealand, multi-billion dollar company Rio Tinto is bailing on Southlanders at the height of an economic crisis," Patterson said in a statement.

"NZ First has consistently warned that Rio Tinto would walk away, just as they did in Australia, when it no longer suited them. And with a 14 month timeframe, this looks like Rio Tinto is using local workers to play hard-ball with New Zealand power companies."

Patterson said it was vital to support the workers who have been affected.

"We will also continue to push to ensure Rio Tinto takes responsibility for the aluminium dross dump in Mataura. It's disgraceful that a huge corporation can behave like this in New Zealand."

Woods said it was the Government's expectation that the site would be cleaned up, which is expected to cost around a quarter of a billion dollars.

The Government appears to accept that Rio Tinto's announcement that it plans to wind-down and close the Tiwai Point aluminium smelter is final.

On Thursday Rio Tinto said it planned to close the smelter in August 2021. More than 1000 are directly employed at the smelter with another 1600 jobs indirectly affected, the company claims.

In a statement more than two hours after Rio Tinto made the surprise decision, the Government gave no signal that it is trying to convince the mining giant to change its mind, saying there was "a degree of inevitability" about the move.

"This day has unfortunately been on the cards for some time now, but nevertheless the final decision is a blow to Southland and all those who work at the smelter," Finance Minister Grant Robertson said.

"The Government will work with the local community to support economic development in the region to help offset this loss."

Robertson added that there "is a degree of inevitability to the decision" with the smelter put up for sale in 2011.

News that Southland's largest employer could close in just over a year has left local leaders reeling, with Invercargill's mayor in shock.

Early on Thursday Rio Tinto announced that it was terminating its electricity contract with Meridian Energy, as it prepared to close the Tiwai Point aluminium smelter in August 2021.

Stew Hamilton, chief executive of New Zealand Aluminium Smelters told RNZ that he did not believe that a deal could be done to keep the smelter open.

"If we're mistaken, the window is open," Hamilton told Morning Report, adding that the window "is closing fast now we've ended the contract with Meridian".

Tim Shadbolt, Invercargill's long time mayor, told RNZ that he "just can't believe it", because he did not think it would come to this saying he never thought it would come to this.

"[I'm] just devastated", Shadbolt said. His initial concern was for workers and "what alternatives there are and it looks pretty bleak at the moment but we're a resilient community and we'll be doing everything possible to look at the options".

Asked if he was disappointed Government didn't intervene, Shadbolt said, "yes, I thought they could have helped, done something to support it.

"They thought if they could only get rid of Invercargill and the lobbying, that would flood the rest of the country with cheap hydro electricity and that's just not going to happen."

Earlier Invercargill deputy mayor Toni Biddle told Newstalk ZB this morning that it was "incredibly disappointing news" - which she learned of at the same time as the media.

Biddle said she felt let down by the Government.

"All we really wanted was a fair operating environment, so we are very disappointed, but we're also very, very resilient down here, so we will stand together as we face this announcement together, moving forward," Biddle said, expressing hope that Rio Tinto could be convinced to change its mind.

"I don't believe it's over until it's over."