TOKYO, Dec 2 (Reuters) - Nippon Steel sees the weak performance at its newly acquired U.S. Steel unit as temporary and remains committed to investing $11 billion to boost its profit contribution to around 250 billion yen ($1.6 billion) by 2028, an executive said.

Japan's biggest steelmaker closed its $14.9 billion acquisition of U.S. Steel in June after an 18-month struggle to win U.S. government approval.

Last month, it widened its net loss forecast for the year to March 31 to 60 billion yen from 40 billion yen after slashing its expected profit contribution from the unit to zero from 80 billion yen.

"Despite recent weak performance, our plans have not gone significantly off track since the acquisition," Vice Chairman Takahiro Mori told Reuters last week.

"The $11 billion capital investment is aimed at addressing areas with high variable costs. U.S. Steel had been underinvested for years, so the investment will definitely produce results."

"We can't provide specific figures for U.S. Steel, but our earlier outlook for underlying profit - excluding inventory valuation effects - of around 250 billion yen by 2028 remains largely unchanged," he said.

Mori said uncertainty over U.S. tariffs and interest rate policy had this year driven an unexpected drop in U.S. steel prices, while an explosion at U.S. Steel's Clairton Coke Works and the unit's high variable cost structure had also weighed on its earnings.

But with one-off factors behind them, an expected market recovery as policy uncertainty recedes, and the full operation of the new Big River 2 plant, U.S. Steel's performance should improve, Mori said. "Things will move in a good direction next year."

To finance the acquisition, Nippon Steel had lined up a 2 trillion yen bridge loan that must be refinanced or repaid within a year. It has already raised 500 billion yen through a subordinated loan to repay part of it.

The recent downgrade in Nippon Steel's annual profit forecast is unlikely to affect financing for the acquisition or investments in India, Mori said.

Asked whether poor earnings might affect potential equity financing, Mori said: "I don't think it will have much impact, but if it does, then a different method would become the best option."

Nippon Steel has identified the U.S., India, and Thailand as core regions for growth.

"We view India's growth over the longer term. Short-term fluctuations in Nippon Steel's earnings do not change our growth strategy in India," Mori said.