Greens leader Nick McKim yesterday called on the Gunns Ltd receiver to publicly release the names of the six companies shortlisted to make final bids on the plantation, woodchip and pulp mill assets, while the Wilderness Society wrote to receiver Bryan Webster asking him to release updated commercial viability information provided to potential investors.

Mr Webster declined to do so, saying it would "not be to the benefit of the sale".

Mr McKim said Tasmanians had a right to know the workplace safety and environmental records of any potential investors, and accused KordaMentha of hiding behind "the furphy of commercial in confidence" by not releasing the names.

"Doubts removal" legislation to extend the pulp mill permit out to 2017 will be debated in a special sitting of Parliament next week, with some parliamentarians warning the debate across both houses could last three days.

It costs more than $3000 an hour to run Parliament, meaning a three-day run could cost $24,000.

Opposition forestry spokesman Peter Gutwein said the cost would not have occurred if the government had acted on KordaMentha's request for assurance on the permit sooner.

"Taxpayers are footing the bill for Labor's desperate strategy to fake a split with the Greens because this legislation should have been dealt with last year when Parliament was sitting and KordaMentha asked for it to be done," Mr Gutwein said.

Premier Lara Giddings said the legislation was delayed until KordaMentha confirmed it had a serious potential proponent, which it did not do until January 13.

"There is clearly an urgency to deal with this issue given that the sale process is scheduled to conclude on March 31, well before the next Parliament could convene," Ms Giddings said.

" If there is any doubt around the validity of the pulp mill permits there is a very real danger that the plantation resource will be sold and we would lose the jobs and investment that would be generated by the pulp mill forever," she said.