Confirmation that 650 jobs are to be lost at a technology company in west Dublin is expected in the next few days.
3Com in Blanchardstown, which currently employs 700, plans to close its manufacturing facility and retain just 50 jobs in research and development.
Workers were given no information by management about the move yesterday, but it is likely to be announced by early next week, it is understood.
Job losses of the scale involved would be a major blow to an area which has seen a significant rise in unemployment over the past year.
It would also be further bad news for the information technology sector, in which other companies are also under pressure because of the global downturn.
3Com makes components for networking systems, a segment of the market which has fared particularly badly over the past three years.
In a statement yesterday, the company declined to confirm the planned job losses, saying it did not comment on speculation.
"As we have consistently said, we are continuously reviewing all our operations on a worldwide basis."
Industry sources, however, said they had no doubt that the company's manufacturing operation was to be closed, and the work outsourced to the far east.
They pointed out that Blanchardstown was 3Com's last surviving manufacturing operation, the company having already closed plants in Singapore and its home base of California.
At its peak, the Blanchardstown plant, which opened in 1990, employed about 1,000. It has received more than €17 million in funding from IDA Ireland, some of which may now have to be returned.
An IDA spokesman said the agency had been keeping in close contact with the company and was "well aware of the pressure they are under".
It had received no confirmation, however, that the manufacturing facility was to close.
"The company says it has not taken a decision at this stage and they told us this morning they have no plans to do anything in the next day or two."
Mr Derek Hanway, manager of Blachardstown Area Partnership, said if speculation about the job losses was confirmed, the loss to the area would be "massive".
"In Blanchardstown over the past 12 months we've seen an increase of about 1,000 in the live register, so people are currently finding it very difficult to get employment in the area," he said.
Ms Joan Burton, Labour's finance spokeswoman and a TD for Dublin West, said the loss of so many jobs would be "disastrous".
"3Com was a hugely important employer in Blanchardstown and this announcement represents a sudden shock to the workforce," she said.
"These redundancies will affect hundreds of families, many of them young couples with children and mortgages."
Fine Gael's enterprise, trade and employment spokesman, Mr Phil Hogan, claimed the job losses were a direct result of the Government's "business-unfriendly policies, which have piled on costs and damaged competitiveness".
"The job losses at 3Com have happened because the Tánaiste has failed to come up with any new ideas or initiatives to deal with the ever-increasing problem of uncompetitiveness. She has failed in her brief to protect business."