Yet again following a widely publicised allegation of tree spiking and the Premier's blaming of environmentalists, Tasmania Police have found no offence could be established because of a lack of evidence, the Australian Greens said.

"Whilst I welcome Tasmania Police's confirmation that no evidence of tree spiking was found and so no offence could be established, Tasmania Police needs to tell the public why no evidence was found when the Premier Lara Giddings said she had seen the tree spikes," Australian Greens Deputy Leader, Senator Christine Milne, said.

"What happened to the evidence which coincidentally was found on the very day the Premier was at Ta Ann?

"If metal was found, then someone must have found it and reported it and the evidence exists or it doesn't or the Premier was set up.

"A report was made to Tasmania Police on the 17th February so some evidence must have been provided to support the claims. Where is it now?

"In the light of these concerns I am pursuing the matter with Tasmania Police.

This pattern of behaviour is a regular occurrence in the long running campaign to save Tasmania's forests. It began with the allegation of the Black River bomb in 1991 and continues to this day.

"At a critical time in any negotiation, allegations of vandalism are made and ultimately no one is ever charged. But in the meantime, maximum media attention is garnered to support the logging industry and environmentalists are blamed, abused and harassed.

"The intention is to take the spotlight off the industry. In this case Ta Ann was under scrutiny for taking logs from high conservation forests and Forestry Tasmania was under pressure to admit that it had overallocated and overcut the forests. Ta Ann shed jobs and tensions were running high.

"What a perfect time to rev up anger against the conservation movement rather than focus on who really is responsible for the disastrous failure to manage Tasmania's forest industry.

"This pattern of behaviour has to stop. I will not stop following up these incidents until the perpetrators of the fake Black River bomb and the vandalism of machinery in the Southern Forests are found."

The letter from Tasmania Police to Senator Milne is attached.