The Tasmanian government has committed to giving corporations the right to sue protesters for defamation, part of a package of anti-protest laws that included legislation last year which beefed up jail sentences and fines for “unlawful” demonstrations.

The state’s attorney general, Vanessa Goodwin, said the government “remains committed to implementing” the change, which would make Tasmania the only jurisdiction in the country where corporations could seek such redress.

“We know that there are radical environmental groups who make a hobby of spreading misinformation to markets with the aim of destroying Tasmanian jobs,” Goodwin said in a statement.

“We will always support the right to free speech but that right to free speech needs to be balanced by the opportunity to challenge clearly false and misleading claims which have the potential to destroy jobs.”

The president of the Tasmanian Law Society, Matthew Verney, said the proposed laws were unnecessary and “impinged on people’s ability to speak freely”.

Goodwin is yet to table any legislation, but Verney said “the noises that have been made about it suggest that it’s going to be very draconian”.

“Ostensibly it would look like the current state government is trying to limit speech and limit criticism of things like the forestry industry. But the worry for us is that it would go far beyond the forestry industry,” he said.

Nationally consistent libel laws were introduced in 2006 removing the right of corporations to sue for defamation, but retaining their right to make a similar claim, injurious falsehood, where it can be proved that a malicious statement had a financial impact.

It is likely that under any new defamation law in Tasmania, corporations would not need to prove economic loss, only that the reputation of the company was disparaged by a false or misleading claim.

The Tasmanian forestry corporation Gunns infamously used defamation laws to sue a group of 20 activists for nearly $7m just days before announcing a new pulp mill. The case collapsed five years later, with Gunns ordered to pay more than $1m in defendants’ legal costs.

The state Greens justice spokesman, Nick McKim, said the Tasmanian government had “learned nothing” from the Gunns case.

“It beggars belief that [Goodwin] is continuing along a path that threatens the rights of Tasmanians to fully participate in some of the most crucial debates about Tasmania’s future,” he said.

“Corporations have had too much power handed to them by parliaments around Australia over recent years, to the detriment of ordinary people and freedom of speech.”

Peg Putt, from the activist group Markets for Change, said the mooted changes were part of a “vendetta” against forest protesters.

She warned the laws would turn Tasmania into a magnet for lawsuits targeting other campaigns, such as those against sweatshop labour and fracking, or highlighting the environmental impact of mining or dredging on the Great Barrier Reef.

The Tasmanian state government passed legislation in November increasing financial penalties and maximum jail terms for protests that “prevent, hinder or obstruct the carrying out of a business activity”.

The original draft of the bill proposed mandatory three-month jail terms for repeat offenders, but was amended after fierce criticism including from the United Nations, which described the bill as “shocking”.

A historic agreement between the forestry industry and major environmental groups calling for an end to the state’s three-decade “forest wars” was torn up by the Hodgman government in September.

The state’s resource minister, Paul Harriss, argued the agreement put too much forest into reserve and that “the use of our forest assets for economic gain is not something of which we should be ashamed”.