New South Wales farmers who cleared land illegally under the old Native Vegetation Act have been granted an amnesty by the Berijiklian government, which has announced it will no longer launch any new prosecutions for breaches of the old law.

Hundreds of cases are believed to be in the pipeline, after the land clearing skyrocketed in north-western NSW ahead of more lenient land clearing laws being introduced by the government in August 2017.

The new law, known as the Biodiversity Conservation Act, brought in a self-assessment system based on maps that showed the most sensitive areas of land. Farmers could self assess before clearing and only the most sensitive areas required prior permission.

The amount of land being cleared for agriculture in NSW soared before the new system came into force and farmers apparently anticipated they would not be prosecuted under the old law.

In 2013-14 9,200 hectares was cleared for new pastures and cropping in NSW. Following the announcement of a review of the Native Vegetation Act, the number of hectares cleared doubled to 20,200 in 2016-17 and in 2017-18 – the first year of the new laws – it had hit 27,100.

This does not represent all the native vegetation lost in NSW. The figures are much higher when losses due to bush fires and forestry activities are included.

The announcement by agriculture minister, Adam Marshall, says there will be “no new investigations under the old Native Vegetation Act from August.”

A spokeswoman for the environment minister said this meant 31 August but other sources said it was from 1 August.

There will also be a review mechanism to ensure those who committed activities that would be legal under the government’s new laws are not unfairly punished, Marshall said.

The Land reported that the NSW farmers conference was told last week there were 164 compliance cases against farmers over alleged illegal clearing with another 100 on the way.

Remediation orders that can tie up land for 20 years will become a last resort penalty. Landholders who were in breach of the Native Vegetation Act may be able to propose other solutions such as set-asides that deliver equivalent environmental outcomes.

The environment movement has accused the government of caving in to the demands of big agribusiness by granting an amnesty to environmental lawbreakers.

“The government has effectively made its deforestation laws retrospective and in the process has endorsed possibly hundreds of incidents of environmental lawbreaking,” said Nature Conservation Council CEO, Kate Smolski.

“This decision undermines the rule of law and sets a dangerous precedent.”

Independent NSW MP, Justin Field echoed the concerns. “This decision sends a terrible signal to those farmers who have done the right thing in the past and invested in protecting and improving the environmental values on their land.”

“Time and again we see the National Party undermining, watering down or not enforcing environmental laws. Their treatment of the Darling River and the failure to enforce habitat protection just reinforces this track record and further undermines the Coalition’s environmental legacy,” he said.

Radio station 2GB has been campaigning against the prosecutions for months, saying they are unfair to farmers.

Prosecutions for land clearing have been deeply resented by farmers, particularly farmers around Moree, Bourke and the northern tablelands.

Five years ago, an environment department officer, Glen Turner was murdered by a farmer Ian Turnbull, after he arrived to inspect land that had been illegally cleared.

Smolski said that “Gladys Berejikilan’s repeal of the Native Vegetation Act has been an environmental disaster.

“They have led to thousands of hectares of wildlife habitat being bulldozed at a time when more than 1,000 native species are now threatened with extinction in NSW.

“Even before the act was repealed in late 2017, there was a massive spike in clearing, presumably because the National party gave big agribusiness an assurance that law breakers would not be prosecuted.

“Today the government has caved into the demands of big agribusiness and dealt another blow to nature and its already appalling record as environmental managers.”