SOME of the state's biggest employers are secretly planning to leave New South Wales after rises of up to 50 per cent in their power and gas bills, with Victoria and Queensland most likely to benefit.

Steel, construction, manufacturing and mining companies are fed up with successive NSW Governments that have not delivered an effective power grid.

Energy Markets Reform Forum spokesman Bob Lim said predicted increases in electricity and gas bills - as well as rises in water charges and rates - had forced big companies to look elsewhere and scale back their operations in NSW.

Mr Lim, who represents dozens of big energy users including Tomago Aluminium, VISY, Bluescope Steel, Kimberly-Clark and OneSteel, said the long-term impact on the NSW economy would be severe.

Job losses and the closure of factories were a reality as companies eyed overseas and interstate options before an emissions trading scheme was introduced, he said.

"Our aim is pretty simple: We want to get real answers from these companies about why they are pushing up bills and not necessarily improving the service for the customer," Mr Lim said.

"There are some members, of significant size, that are considering whether to stay in NSW or take their operations offshore."

Sources have said big steel operators and manufacturing companies are considering moving to escape Sydney's high living costs.

Victoria, with its healthy development subsidies and cheaper power, is in a prime position to poach them.

Last year, OneSteel and Bluescope Steel axed hundreds of jobs and cut back production in NSW.

As the economy improves, they are seeking lucrative opportunities for shareholders.

Queensland Treasurer Andrew Fraser said he would roll out the welcome mat for NSW companies.

"We are pro-business. No other state is in the same field as us. They wouldn't even know where the stadium is," Mr Fraser said.

"In 2008-09 alone, the Queensland Investment Incentives Scheme saw seven leading companies and projects come to Queensland, including Rio Tinto and Tasman Aviation Enterprises."

Mr Lim said his client firms' electricity bills had increased between 30 and 50 per cent.

Instead of fixed rates, energy retailers and high-use companies sign individual contracts worth millions of dollars.

"In one case, an energy company explained the extra money would go into the residential grid to make sure the network didn't fail during a two-week period in summer when people used their airconditioners," Mr Lim said.

"That really isn't an adequate response. The high-use businesses are effectively paying for services that they don't have anything to do with."

Opposition energy spokesman Duncan Gay said he would not be surprised if big business fled NSW after being forced to bankroll an overdue energy infrastructure upgrade.

"NSW Labor has ripped nearly $14 billion out of the state's energy retailers in dividends and taxes and failed to re-invest this in our ageing infrastructure," Mr Gay said.

An EnergyAustralia spokesman said NSW electricity providers offered reasonable rates to large companies in comparison with other states.

A spokesman for Energy Minister Paul Lynch said that customers who had difficulty paying their bills could seek "concessions and rebates" through the Government's $800 million assistance package over the next five years.