Hitachi Ltd. will post pretax losses of 100 billion yen in the 1998 business year to next March 31, marking its first plunge into red ink for the postwar period, company officials announced in revised earnings forecasts Thursday.

The major electric machinery manufacturer had earlier projected unconsolidated pretax profits of 30 billion yen for the 1998 business year.

In the throes of its deepest crisis, the electronics giant also announced a major restructuring plan that includes cutting 4,000 workers in the current business year and slashing fixed costs by 10 percent, or 140 billion yen, by the end of the next business year.