The claims emerged after meetings last week between the Kurri Kurri and Tomago aluminium smelter management and Hunter Business Chamber chief executive Peter Shinnick.

Mr Shinnick told The Herald this week that the mining tax and other state and federal Labor policies had killed off $4 billion in work at Kurri and a Tomago Aluminium potline extension worth $600 million.

He was joined yesterday by federal Liberal MP Bob Baldwin, who said Hunter industries needed political certainty to invest and expand.

"Mr Rudd's emissions trading scheme and super-tax policies have created economic uncertainty," Mr Baldwin said.

But a representative for Tomago Aluminum said work on the potline expansion had stopped at the "pre-feasibility study" stage in 2008.

"Tomago Aluminium hasn't scrapped any projects because there are no current business plans for a $600 million development," the representative said.

Australian Workers Union branch secretary Richard Downie said things were tough in the aluminium industry.

"But our national secretary Paul Howes, met Kurri Hydro managing director Harald Bentzen a couple of weeks ago and the message he got is very different from the one the business chamber is pushing," Mr Downie said.

Tomago had just agreed to pay increases of more than 18 per cent over four years.

Kurri had a new 10-year electricity deal and Tomago was confident of following suit.

Kurri was "confident" that plans to double the size of the smelter, first unveiled in early 2008, would eventuate "in the long term".

Mr Downie conceded that Kurri wanted to cut the smelter workforce by natural attrition.