An exclusive Seven News investigation has revealed the State Government was considering selling state assets six months before the state election, despite denials it was pre-planned.

Anna Bligh didn't unveil plans to privatise $15 billion worth of publicly owned entities until after Queenslanders re-elected her. Since then, both the Premier and her senior ministers have steadfastly rejected suggestions they were planning the fire-sale before last March's election.

An exclusive Seven News freedom of information investigation tested the Premier's claim that she "didn't have a secret plan" to sell off state-owned assets. That investigation revealed the Queensland government was warned six months before last year's election that it might have to sell off public assets to deal with mounting debt levels.

On Monday night, Seven News revealed that a cabinet discussion paper, dated October 2008, warned senior ministers, including the Premier, that Queensland's coffers were facing "high rising debt levels", with "no capacity for repayment".

Options for dealing with the problem were outlined in the document, and they included asset sales.

As early as December last year, Anna Bligh told Seven News it was not until after the election that asset sales were considered.

"What I did after the election was sit down with Treasury and do weeks and week of hard yards looking at all the alternatives," Ms Bligh said.

But documents uncovered by Seven News reveal some of those 'hard yards' were being done long before the last election.

In April 2008 Treasurer Andrew Fraser met senior executives from United States based company Hancock Forestry, where the company expressed "very keen interest in being able to acquire Queensland Forestry assets".

According to an email exchange, "The Treasurer in responding indicated that 'thinking' on forestry was not closed", and went on to highlight that "the Government did not have a slavish devotion to any particular philosophy".

Union spokesman Peter Simpson said the documents represented a "smoking gun" against the Government, but Treasurer Andrew Fraser said it simply showed an unchanged policy.

"It's only evidence of the fact that the government's policy hasn't changed through it's time in office," Mr Fraser said.

The email correspondence with the US forestry company also states that Mr Fraser "highlighted that at several points over the past 10 years, the Govt had decided to exit certain asset classes, e.g. recent Airports announcement."

The Treasurer insisted he told Hancock executives that Queensland Forestry wasn't for sale, but not in the email obtained by Seven News.

"There was a discussion about the way in which the government approached privatisation, and that is that we deal with it on a case by case basis - have done throughout our time in government and would do so into the future," Mr Fraser said.

The revelations will give more ammunition to those opposed to the asset sales, including unions who could soon call a special ALP conference to have the sell-off plans overturned.