AGL's decision to dump its coal seam gas projects in NSW came despite unflinching support from state agencies, members of an anti-CSG group said.

Years of battling the company and regulators such as the Office of Coal Seam Gas and the NSW Environmental Protection Agency required a constant stream of freedom of information requests and endless research, John Watts, a spokesman for Groundswell Gloucester, said.

The government was "at every stage" was prepared to approve AGL's proposed gasfield near Gloucester in the state's mid-north coast region, Mr Watts said.

"It's the approval and regulatory authority, and the government gets the benefits of any royalties," he said. "So there's not interest in them stopping it."

AGL had planned 110 CSG wells near Gloucester as stage one of a $1 billion project. On Thursday, the company ditched that plan, announced it would sell its Queensland CSG assets and said it would exit its existing Camden gasfield by 2023, more than a decade early.

Groundswell Gloucester compiled what it described as a dossier of governance failures during an eight-year fight, including a planning rule change that solely benefited AGL.

"People think the EPA is out there monitoring [projects like AGL's] but they are not," Julie Lyford, chair of the group, said.

Philip Pels, an independent hydrogeologist, who warned about the risks of drilling CSG in a fractured basin such as Gloucester's, said the state relied on evaluations by private consultants hired by proponents of CSG, coal mines and other projects "to show that they were not going to bugger up the environment".

"Consultants, even with the best will in the world, are going to bend to the [company's wishes] or they would not get the next project," Dr Pels said. "It's kind of a fatal flaw in the system."

A spokesman for Anthony Roberts, Minister for Industry, Resources and Energy, said the Liberals and Nationals government had put "independent scientific analysis and information at the forefront" of regulation of the sector.

"The independent NSW Chief Scientist & Engineer, Professor Mary O'Kane, delivered a report into the CSG industry with its recommendations now either in place or in the process of being implemented," he said.

"As outlined in the [new] Gas Plan, we have introduced a Strategic Release Framework that will examine economic, environmental and social factors, with community consultation conducted upfront, before a proposed exploration area is released for expressions of interest," the spokesman said.