Under the $276 million intergovernmental agreement signed in August, 430,000 hectares was to be protected in the short-term while 570,000 hectares was considered for permanent protection.

But under a deal signed yesterday 43 coupes, or 1950 hectares within the 430,000, will be logged up until June.

That's angered environment groups and the Greens Party, which consider it a failure by Prime Minister Julia Gillard and Premier Lara Giddings to keep their written word.

Acting Premier Bryan Green described it as a milestone for the conservation movement while also providing certainty for the industry.

``People on the other side of the argument will ague that 99.5 per cent (of 430,000 hectares) isn't enough. Well I would say that most fair-minded Tasmanians and Australians would,'' he said.

Mr Green acknowledged that the governments had not upheld their earlier agreement to compensate industry for any coupes proven to be required within the 430,000 hectares.

However, he said the conservation deal was still ``in the spirit of the agreement''.

Australian Greens leader Bob Brown described the news as ``a death warrant'' dressed up as a conservation agreement.

He said 20 square kilometres of high conservation value forests would be destroyed - equivalent to 1000 Melbourne Cricket Grounds - by June 30.

Similarly, acting Tasmanian Greens leader Tim Morris said it was bitterly disappointing that the two Labor leaders had failed to deliver on their own agreement.

A spokeswoman for Ms Gillard said while the Greens might be prepared to put the entire area in jeopardy by walking away from the agreement, ``the Prime Minister was not''.

The news is tipped to result in more protests with environment groups involved in the process labelling it a failure.

Forestry Tasmania managing director Bob Gordon said the state-owned business had signed up to yesterday's deal as it was satisfied it would still be able to meet ``it's legal contractual, fiduciary and environmental obligations''.