Along with its domestic rivals and major international oil and mining companies, Mitsubishi Corp has been caught off guard by steep falls in the prices of goods from oil to iron ore as China's economic growth has slowed.

Mitsui & Co Ltd on Wednesday predicted its first net loss since after the slide in energy and metal prices forced it to book 260 billion yen (£1.6 billion) in writedowns, Sumitomo Corp more than halved its full-year profit forecast last month and Marubeni made 73 billion yen of writedowns for the April to December period .

Mitsubishi Corp's group net loss is now forecast at 150 billion yen, against a previous estimate for a 300 billion yen profit, as it plans to take an impairment loss totalling 430 billion yen, its biggest such loss.

That will mark the first consolidated net loss since the company was established in 1954, a spokesman said.

"The resource prices have fallen more than we had anticipated," President Ken Kobayashi told a news conference. "We've taken losses on all the assets with potential writedown risk as of now."

Accepting responsibility for the results, Kobayashi is taking a 50 percent pay cut while all other executives have had bonuses scrapped, but the company kept to its annual dividend forecast of 50 yen per share.

The 430 billion yen impairment losses include a 280 billion yen writedown on a stake in Chilean copper company Anglo American Sur and 40 billion yen on the Browse liquefied natural gas project in Australia.

"The copper losses reflect our revised long-term price estimate to below $3 per pound," Kobayashi said, adding that its assumption for the coming year is set at $2 per pound.

To cope with the commodity downturn, Mitsubishi could opt to sell non-core resource assets such as ferrochrome, aluminium and bauxite, he said.

Nomura Securities analyst Yasuhiro Narita said that writedowns by Mitsubishi and Mitsui had been expected but that the size of the losses were bigger than forecast.

"Trading firms will need to focus more on the areas where each of them has a strength," he said.

Analysts have said that hefty losses from weak markets could deter Japanese trading houses from investing in energy and metals projects.

Shares in Mitsubishi fell 4.1 percent to end at 1,920.0 yen before the announcement. Shares in Mitsui, which unveiled its revision after the market closed on Wednesday, lost 7.5 percent, underperforming a Nikkei index down 0.6 percent.

(Reporting by Osamu Tsukimori and Yuka Obayashi; Editing by Stephen Coates, Joseph Radford and David Goodman)

By Yuka Obayashi and Osamu Tsukimori

Stocks treated in this article : Marubeni Corp, Mitsui & Co Ltd, Mitsubishi Corp