Sumitomo, which holds a 47.67% stake in the project through its unit Summit Ambatovy Mineral Resources Investment (SAMRI), has faced a series of delays in its ramp-up.

But the latest evaluation loss on the unit on a parent basis under Japanese accounting standards will not affect its group profit estimate for the current financial year as it has already wrote off a similar size of impairment losses under the International Financial Reporting Standards (IFRS) by last financial year, a company spokeswoman said.

Sumitomo's chief financial officer, Koichi Takahata, said in August that the Ambatovy nickel plant produced 9,000 tonnes in the April to June quarter, and it still expects annual output of more than 40,000 tonnes for the year to March. [nL4N24Y1F9]

($1 = 108.2300 yen)

(Reporting by Yuka Obayashi, editing by Louise Heavens)