The timber magnate behind a $1.7 billion pulp mill in northern Tasmania says construction on the project should begin early next year.

Gunns chief executive John Gay today said that applications for operational permits would be submitted to the state and federal governments within six to eight weeks.

Mr Gay said he was confident that construction of the mill would commence in January.

"We are currently going through the process of understanding the permits," Mr Gay said.

"We are working to a timeline of about six to eight weeks and we have no issues at all with the state or federal conditions imposed on the mill."

Federal Environment Minister Malcolm Turnbull earlier this month gave the go-ahead for the pulp mill, subject to 48 conditions.

Tasmania's Premier Paul Lennon last week announced a 20-year wood supply deal for the Tamar Valley mill, under which Forestry Tasmania, the state timber authority, would provide 1.5 million tonnes of native and plantation timber annually.

Gunns would pay a base price of nearly $16 a tonne for native timber and $32 for plantation timber.

Prices would be adjusted every six months, depending on international pulp prices.

Gunns would also be expected to pay for harvest and transport costs, including the potential to build new roads.

Mr Lennon said the deal would not end old growth forest woodchip exports from the state.

This has angered the Greens.

"What Tasmanians were not told in the carefully pitched announcement on the pulp mill wood supply is that Tasmania will continue its disgraceful trade in export of old growth forest woodchips at the level of half a million tonnes a year even if the pulp mill is built," Greens leader Peg Putt said today.

"And native forest woodchip export levels will be even higher.

"Also very carefully glossed over by the Lennon government is that old growth material will be burnt on the pulp mill site in the co-located forest furnace which was approved as part of the pulp mill development application."

Ms Putt urged people not to "fall for the political trickery" that implies old growth logging for woodchip will cease if the pulp mill is built.

AAP