The company says it is shedding 140 jobs

The announcement by American firm Huntsman, which owns the plant in Whitehaven, comes just six months after 45 jobs were axed.

It will mean the plant, which used to employ 2,000 workers, will be manned by just 10 people by the end of 2006.

Ged Caig, spokesman for the GMB union, said the move was a "betrayal" of workers. The jobs will be phased out over the next 15 months.

In March, the firm revealed �11m was being invested in the detergent-making operation, but most of that investment will now be withdrawn.

'Totally betrayed'

Site director at the plant, Michael Carter, said he "regretted" the decision, but that it was necessary if the factory was to remain viable.

But Mr Caig condemned the move. He said: "Only a few months ago workers agreed to retrain and multiskill.

"It was a hard pill to swallow but they said okay if it would keep the plant viable.

"We are already at an advanced stage of the negotiations and then the workers are told this - they feel utterly and totally betrayed."

A statement released on behalf of Huntsman blamed an "increasingly competitive environment" for the job losses.

Huntsman took over the site three years ago promising a bright future for chemical production in the town.

But last year the wind-down of the operation began when 85 jobs were shed.