Ninety workers are set to lose their jobs following One Steel’s announcement to close its Somerton plant in Victoria.

A further 180 jobs also face the chopping block at the One Steel mill in Newcastle, New South Wales.

AMWU Victorian Secretary Steve Dargavel says the job losses are senseless because the mill is still viable.

"The closure's unnecessary because the chain of production for the merged owner is profitable," he said.

"The company nevertheless has decided to get out of this part of steel and we've got over 100 workers that are losing their jobs."

Mr Dargavel says the company is abandoning workers who have spent decades building up the company.

"There isn't another plant like it in this country and so it won't be easy for them to retrain and get alternative employment," he said.

"It's a significant concern when companies like this close, because the workers face the difficulty of having to adjust and to try and find alternative employment."

AMWU member Velu Achary said he was completely surprised by the company’s announcement.

“Nobody expected this. It just came out of the blue. Our jobs are highly specialised and it’s going to be difficult getting another job.

Mr Achary is concerned about the future as he is his family’s breadwinner and has two young children.

“It's definitely going to be hard for us", he said.

The plant is set to close by the end of 2008.