The losses include about 10 billion yen due to lower-than-expected production and about 5 billion yen on the disposal of some fixed assets and appraisal of ore inventories, Sumitomo Chief Financial Officer Koichi Takahata told a news conference.

For the current business year to end-March, Sumitomo lowered its estimate of Ambatovy's nickel output to 38,000-40,000 tonnes from 40,000-43,000 tonnes.

Takahata said output is expected to grow to around 46,000 tonnes next year starting in April. Sumitomo owns a 47.67 percent stake in the project.

(Reporting by Yuka Obayashi; editing by Richard Pullin)