A nickel mine in southern Western Australia is set to close, with more than 300 jobs lost.

First Quantum Minerals confirmed on Monday that its Ravensthorpe Nickel Operation (RNO), 500km south-east of Perth, would be placed into care and maintenance.

In a statement, the Canadian company said about 330 roles would be "made redundant".

The company cited lower nickel prices projected for the next few years and higher operating costs.

"It is anticipated all production will cease by late May, with various activities underway in the coming weeks to ensure a planned, safe wind-down of processing and other areas," a First Quantum spokesperson said.

"Despite RNO's best befforts to maintain operations ... the site is incurring significant current and projected losses.

The spokesperson said First Quantum acknowledged it's decision would have a significant impact on its employees and their families.

"A smaller, dedicated care and maintenance team will be appointed from current RNO employees to ensure the site is safe and preserved for a future re-start."

The company said it would continue to engage with the Ravensthorpe and Hopetoun communities, and pledged a "large proportion" of the care and maintenance team would continue to be locally based.

It comes about three months after mining operations were wound back in Ravensthorpe.