The Tasmania Government is under fire after the signing of another secret cut-price power supply agreement for a big multi-national.
There is speculation the deals do not include the carbon tax.
Pressure is now mounting for the same offer to be extended to the state's other businesses.
On Thursday the State Government announced 500 jobs at Rio Tinto's Bell Bay smelter were safe thanks to an electricity supply deal with Hydro Tasmania.
Last month BHP Billiton renegotiated the supply contract for its TEMCO manganese smelter.
Geoff Fader from the Tasmanian Small Business Council has reacted angrily to Rio Tinto's deal.
"If one business in Tasmania can buy carbon tax free from the Hydro, why should not all the other businesses in Tasmania?" he said.
The Premier Lara Giddings has refused to detail the terms of the deal.
"Details of the actual arrangements are, of course, commercial in confidence and I understand that's frustrating for people," she said.
Opposition spokesman Matthew Groom says big business should not be singled out for help.
"It is hypocritical of the government to provide carbon tax relief for big business on the one hand and deny carbon tax relief for households and small businesses on the other," he said.
Greens spokesman Kim Booth has called for cheaper power to be extended all Tasmanians.
"You know it's quite plausible that Tasmania is able to offer better pricing arrangements because we don't have a carbon price attached to Hydro's generation," he said.
But Ms Giddings insists most Tasmanians will receive assistance.
"Nine out of 10 Tasmanian households are being assisted through this next period."