Fifty-eight jobs could be lost at Unilever's Petone laundry powder manufacturing site if a proposed closure goes ahead.
Company chief executive for Australia and New Zealand Clive Stiff says a consumer move toward liquid laundry detergent and away from powder is to blame.
"We have done what we can to address this changing market, however regrettably we are now at a stage where closing the Petone factory appears to be the only viable option available to us."
Under the proposal, production would continue at the site for up to 18 months, followed by a decommissioning period of up to six months.
Mr Cliff says the company will support staff through "a range of measures" as it works through its plan to close the plant.
The site could be shut by the end of 2015.
Unilever has had a long history in the Petone area with the production of Sunlight, Lifebuoy and Rinso soap powder beginning in 1919.
Around 150 non-manufacturing staff in the company's Auckland office and in sales will be safe regardless of the decision, Mr Cliff says.