SIPTU has described as "deeply worrying" an announcement by Fruit of the Loom that it is to put all its remaining 1,900 workers in plants in Donegal and Derry on a three-day working week.

Donegal suffered a devastating blow last December when Fruit of the Loom announced 770 job losses at four plants in the county and, in a deal agreed then with IDA Ireland, it guaranteed 700 remaining sewing jobs only until the end of this year. Another 600 jobs in fabric production were guaranteed until 2006.

Mr Sean Reilly, SIPTU branch secretary, said: "The fact is that 700 sewing jobs are under threat in Co Donegal. Nobody would deny that. And in that context, this announcement is deeply worrying."

Practically all of the company's 1,900 workers in Ireland - 1,400 in Donegal and 500 in Derry - are to be put on a three-day working week from Monday week. A statement given to employees yesterday said that the company anticipated "a return to full-time working by this year's end", but some workers feared that this did not necessarily mean they would all be put back on a five-day week. In the run-up to last December's announcement, many workers had been working for just two or three days per week. A Fruit of the Loom spokesman said yesterday that "the reintroduction of short-time working" was due to "production requirements being significantly reduced because of forecasted sales and current inventory positions".

A spokesman for the Tanaiste, Ms Harney, said she was disappointed by the announcement, but that it was "not a breach of existing arrangements between the company and the IDA in terms of maintaining long-term employment".

Periods of short-time working at this time of the year are not uncommon in the clothing industry generally, and they have occurred practically every year at Fruit of the Loom.

Mr Reilly said he was aware that the plants were not very busy over recent weeks, but workers did not expect the introduction of a three-day week so soon.

Fruit of the Loom effectively transferred its T-shirt sewing operations to Morocco last December and yesterday's statement said the Moroccan employees had also been put on a "reduced working schedule".

All of the 770 workers affected by last December's announcement have not yet lost their jobs. Plants at Malin and Milford closed down over the summer, but up to 200 workers remain at the Raphoe plant. It was also announced yesterday that the Raphoe plant would close down fully from next Friday. The remainder of the company's workers in Donegal are in Buncrana.

The Tanaiste's spokesman said that efforts were continuing to bring other jobs to Donegal to replace those lost at Fruit of the Loom.