All planned curtailment will be complete by the end of September, Alcoa claims and one of the company's plans involves the permanent closure of one potline at the Massena East plant in New York.

Bob Wilt, Alcoa's president of global primary products, said the planned cuts, which were announced in May, are designed to maintain the company's competitiveness in the face of depressed aluminium prices, including premiums, which, he said, 'have fallen to four-year lows'.

Once the Massena and Brazilian cuts have taken place – 40kt and 124kt respectively – Alcoa will have 16% (just over 647kt) of production capacity idle. Alcoa has a 2015 goal of lowering its position on the world aluminium cost curve by 10% and the alumina cost curve by 7%.

The Massena potline earmarked for closure employs 100 people, but layoffs are unlikely and the local branch of the United Steel Workers union seems relaxed about it as a $600 million modernisation plan for the plant is still on the agenda and paves the way to manufacturing jobs long-term.

"We continue to operate in an uncertain, volatile market," Wilt said.