By Sherin Sunny and John Biju

(Reuters) -Lynas Rare Earths ( LYSCF ) warned on Tuesday of a one-month production shortfall this quarter due to significant power supply disruptions at its Kalgoorlie processing facility in Western Australia.

The production shortfall could be a potential setback for the world's largest rare earths producer outside China as it tries to ramp up output amid a growing push from countries to reduce their reliance on China.

Lynas said its Kalgoorlie facility faced a substantial rise in power supply disruptions in 2025, with outages in November resulting in a significant loss in mixed rare earth carbonate (MREC) production.

The company expects the disruptions to impact production of finished goods at its Malaysian facility this quarter. MREC produced in Kalgoorlie is processed at Lynas Malaysia's advanced materials plant in the industrial town of Gebeng.

"Lynas is working constructively with the WA government and Western Power to identify causes of recent outages and options to improve power availability to the Lynas plant," the company said.

"Whilst these are being progressed on an urgent basis, even on a best-case scenario, they will not be in place in time to improve this quarter's forecast production."

Lynas recorded total rare earth oxide output of 3,993 metric tons and neodymium and praseodymium (NdPr) output of 2,003 tons for the September quarter. It reported sales revenue of A$200.2 million ($129.19 million) for the quarter.

Analysts at Canaccord Genuity cut their NdPr production forecast for the December quarter to 1.8 kilotons (kt) from 2.7 kt previously expected. Revenue expectations were lowered to A$220 million from A$280 million.

Shares of Lynas closed 0.1% lower at A$15.02 after falling more than 2% earlier in the session. The broader benchmark index edged 0.1% higher.

($1 = 1.5497 Australian dollars)

(Reporting by John Biju and Sherin Sunny in Bengaluru; Editing by Alan Barona and Subhranshu Sahu)