* Warning follows surprise write-downs forecast in Sept
* Annual profit estimate unchanged at $85 mln
* Non-resource businesses doing well - CFO (Adds quote, details on write-downs, background)
TOKYO, Feb 3 (Reuters) - Japanese trading house Sumitomo Corp warned on Tuesday that it may take additional impairment losses on its energy and metal assets due to slumping oil and iron ore prices, although its annual profit forecast remained unchanged.
The warning came after its surprise forecast in September last year that it would write-down about 240 billion yen ($2.05 billion) in the value of its assets, mainly in energy and metals.
Like international oil majors and mining companies, Japan's trading companies have been caught flat-footed by the rout in commodities, with oil down more than 50 percent and copper falling about 23 percent since the middle of last year.
"We may need to take an additional write-down on some of our stakes in resource assets due to falling prices of oil and other commodities. But we are keeping our full-year profit forecast as our non-resource businesses are doing well," Sumitomo Chief Financial Officer Hiroyuki Inohara told an earnings news conference.
Inohara said the company might book an impairment loss on its stake in a North Sea oil project and its share of the Marcellus shale gas project in the United States.
The company might also take an additional write-down in the value of its stake in a U.S. shale oil venture and a Brazilian iron ore operation, he added. Sumitomo said in September it would suffer a hefty impairment loss from the Brazilian project.
Inohara did not say how much the additional losses could be.
The company stuck to its forecast of net profit for the year to end-March of just 10 billion yen ($85.46 million), compared with a profit of 223 billion yen a year earlier and a 12.3 billion yen mean estimate of 10 analysts polled by Thomson Reuters.
Last September, Sumitomo shocked investors by cutting its annual profit guidance by 96 percent due to losses on a U.S. shale project and sharp declines in iron ore and coal prices.
For the April-December period, it reported a net loss of 10.26 billion yen after booking impairment losses totalling 193 billion yen, which included a 174 billion yen write-down in the value of the shale oil project in the Permian Basin in Texas.
Inohara said the company had no plan to write down the value in the Ambatovy nickel project. ($1 = 117.0100 yen) (Reporting by Yuka Obayashi; Editing by Stephen Coates)