Greens leader Christine Milne says the "secretive, backward-looking" coalition government is setting up a pattern of suppressing information in its first weeks in power.
Reports on Monday suggest the government will review competition laws with a view to banning secondary boycotts by environmental and consumer groups.
This could stop campaigns such as Get Up's 2011 ads which linked furniture retailer Harvey Norman with the destruction of old growth forests.
Senator Milne said the move would deny markets information.
"Efficient markets work when they have the best information," she told reporters in Canberra.
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"All the environment movement's ever done is gone out to the markets and told people where the timber is being sourced and those markets make their decisions accordingly."
She said any such move would hinder the competitiveness of Australian timber businesses because the world market wanted to be sure it wasn't buying wood from old growth forests.
"They've got a secretive, backward-looking government and in this day and age he will be really challenged on his ability to try and shut down information," Senator Milne said.
The Wilderness Society said it was an odd move from a pro- free-market government.
"It will make martyrs out of advocates and pariahs out of companies seeking to cover up the true environmental footprint of their products," national director Lyndon Schneiders said in a statement.
