TAP into a Better Tasmania spokesman Bob McMahon said at the first sign of further developments, TAP would be there.

"If the government wishes to introduce particularly stupid laws to curtail us, we'll welcome that," Mr McMahon said.

He said the group had plans to disrupt the "incredible illegitimate process that's gone on in Tasmania", but refused to give details.

"You will soon find out," he said.

"Probably within the next two weeks.

"It'll just be a little token of what we might expect for the future."

A federal government decision on the three remaining modules for the $2.3 billion project's environmental impact management plans will be known on Thursday.

The decision represents the last legal barrier to the proposed mill.

A decision was expected last week, but Environment Minister Tony Burke extended the deadline because Gunns wanted tougher environmental controls than those in the original application.

On Friday, Gunns did not detail the stricter controls it had sought but managing director Greg L'Estrange has said the company wanted to build the mill using the best available technology with the best environmental controls available.

Bass Greens MHA Kim Booth said on Friday that he would withdraw his support from the Labor-Greens alliance if the government used any public money for the mill.

Mr McMahon said the idea of the pulp mill was disgraceful.

"I mean how productive is a hectare of fibre-producing trees, such as Eucalyptus nitens, compared to say a field of anything," he said.

"Hay is more valuable than pulp fibre."

Mr McMahon said if the government went ahead with the mill, it was making a foolish decision.

"To create a few jobs, you are going to lose an awful lot of other ones," he said.

"It's a crazy game and it was only ever something that was a result of political pressure."