The Insight Economics pulp mill assessment was conducted in conjunction with the Monash University's Centre of Policy Studies and released by the company yesterday.

It presents the proposed pulp mill project as a major boost to the Tasmanian economy.

It comes at an opportune time for Gunns on the eve of an anti-pulp mill rally in what environmentalists have promised will be a new, long campaign.

Pulp the Mill, organiser of Sunday's protest rally at the Batman Bridge reserve, says it is expecting a huge turnout to the rally.

Environmental groups promised to bring on an anti-pulp campaign bigger than the Franklin Dam blockade after Gunns was granted the last federal environmental permits it needs to start construction of the mill last week.

The economic assessment of the project found that:

•Total value of the project to the gross state product of $9.9 billion by 2030 would be a return of four times the original investment.

•Total value to Northern Tasmania would be $3.7 billion and $2.1 billion to the North- West region.

•It would generate more than 11 per cent higher annual employment each year to Northern Tasmania than if it hadn't gone ahead.

•The mill would generate $597 million in taxation revenue for the state government and $397 million for the federal government.

Gunns managing director Greg L'Estrange said that the report indicated that the pulp mill would be the single biggest shot in the arm for the Tasmanian economy for a long time.

He said that Gunns' task was to find a way to secure the economic benefits of the mill and work hard to mitigate what some people saw as its risks.