Two of Australia's biggest supermarket retailers say the Federal Government have not consulted them about the proposed carbon tax and are calling on the Government to reveal details about the tax before implementation.

The heads of Woolworths and Cotes have also expressed their concern over how the retail business will be impacted by the lack of certainty over the carbon tax. The retail conference held yesterday in Sydney also revealed the reservation the big retailers have over the tax and how they are finding it difficult to meet the federal government's 12-month deadline.

Cole's managing director said that the retailers are finding it hard to gauge what the tax will mean for their businesses if the government doesn't reveal how the carbon tax will affect the market. Cole's was looking for ways to mitigate the cost of the tax.

"We don't want to pass costs on to the consumer, so we're going to try and suppress that as much as possible ... but it's very difficult to estimate what that impact might be."

Adding to the growing criticism over the carbon tax, incoming Woolworth's chief executive Grant O'Brien added that the government hasn't spoken to retailers on how the tax will be implemented. Woolworths is trying to prepare but there is no reliable way to tell how much of the tax will be passed on to their customers.

"There's no point constructing a model and typing in numbers until such time as we know at what point some of these taxes are actually going to be passed on to the consumer."

He also said that the time frame government gave retailers is too short to adequately execute the tax properly.

Bunning's chief executive John Gilliam expressed his concern over what the tax could mean to an already lackluster market. Other panelists including David Jones chief executive Paul Zahra agreed that general consumer sentiment is weak.

The government has yet to reveal a final plan for the proposed carbon tax even the market price mechanism for carbon is still being discussed even though the Labor government wants the tax implemented by July 2012.