NEW YORK — Shares of Nortel Networks fell 15 percent Wednesday after the maker of optical and wireless network equipment said it won't meet the sharply reduced profit forecasts set just a month ago and now plans to eliminate 5,000 more jobs on top of the 10,000 already cut since the start of 2001.

The warning Tuesday by the Canadian company, a bellwether for the technology industry, echoed the increasingly dire projections coming from Cisco Systems, the world's leading producer of network equipment for the Internet.

Those worrisome updates come amid a fragile recovery on Wall Street, which has been ravaged by fears of a potential economic recession.

In addition to revealing that profit and revenues for the first three months of the year are coming in even weaker than they seemed a month ago, Nortel also made the unsettling suggestion that business conditions have turned too difficult to make any worthwhile forecasts for the rest of 2001.

"Given the poor visibility into the duration and breadth of the economic downturn and its impact on the overall market growth in 2001, it is not possible to provide meaningful guidance for the company's financial performance for the full year," John Roth, president and chief executive officer, said in a statement.

The announcement also said Nortel will cut 5,000 more jobs in addition to the 10,000 that were announced since the start of the year, the bulk of which have already been made, the company said Tuesday.

A company spokesman said it wasn't immediately clear how many of the 5,000 positions would be eliminated through layoffs and how many through resignations, retirement and attrition.

The cost savings from the cutbacks won't be felt until next quarter, Nortel said.

In mid-February, Nortel slashed its first-quarter forecasts to $6.3 billion of revenue and an operating loss of 4 cents per share.

Now the company expects to post first-quarter revenues in the range of $6.1 billion to $6.2 billion and an operating loss of 10 cents to 12 cents per share.