Plagued by dwindling demand and prices of steel products at home and abroad, major steelmakers on Friday separately announced they are significantly lowering their earnings projections for fiscal 1998.

Nippon Kokan K.K. (NKK), the nation's second largest steelmaker, said that its consolidated net losses will be 113 billion yen, not 109 billion yen as projected in November.

Consolidated sales were revised down from 1.835 trillion yen to 1.8 trillion yen, and pretax losses are expected to grow from 35 billion yen to 43 billion yen on a consolidated basis. In explaining the revision, NKK said that domestic and overseas prices have fallen sharper than expected.

Meanwhile, Kobe Steel Ltd., the fifth largest steelmaker, said that its consolidated net losses will grow to 34 billion yen from 26 billion yen.

Sumitomo Metal Industries Ltd., the nation's fourth largest steelmaker, said that its consolidated net losses will grow from 30 billion yen to 74 billion yen. Sumitomo Metal blamed the downward trend on the domestic economic slump, decreasing exports to Southeast Asian countries and the yen's recent appreciation.

According to the Japan Iron and Steel Federation, the annual production of crude steel by the nation's industry is estimated to be 91 million tons for fiscal 1998, down 11 percent from the previous fiscal year.