Mt Thorley Warkworth, Muswellbrook Coal, Ravensworth Operations, Rix's Creek North Coal Mine and Rix's Creek South Coal Mine have fallen short of environmental management and rehabilitation compliance.

In a damning assessment of the mines, the NSW Resources Regulator uncovered ongoing delays in rehabilitation works, erosion features ignored, unexplained areas of low species diversity and poor record keeping.

Inspectors raised serious concern about rehabilitation works at Muswellbrook Coal, owned by Japanese mining company Idemitsu.

"An inspection identified several risks to the successful rehabilitation of the mine that may require considerable time and resources to mitigate/rectify," the report states.

"The risks are of concern given how close the site is to mine closure."

Inspectors carried out 112 unannounced visits to mines and petroleum sites across NSW in June issuing 54 work health and safety improvement notices, including ten in the Hunter Region.

There were 11 mining inspections carried out in the Hunter and six notices issued to five mines for rehabilitation failures.

Lock the Gate spokeswoman Georgina Woods said it was an "unacceptable strike rate and utterly damning for the industry".

"These coal mines are owned by some of the biggest mining companies in the country, and it is unacceptable for them to be failing on their rehabilitation and environmental management," she said.

"When rehabilitation falls behind or is done poorly, it leads to an increase in air pollution and leaves future generations with the burden of cleaning up the mining companies' mess."

Coal miners have traditionally provided Australian regulators with cash deposits or bonds that are held by governments or banks as a collateral guarantee that taxpayers will not be left footing the bill for rehabilitation at the end of a mine's operating life.

Concern about the adequacy of rehabilitation funds has been fanned in recent years following the bankruptcy of major coal miners.

Hunter Communities Network spokeswoman Bev Smiles said the bond system needed overhauling so it was transparent.

"Rehabilitation of these mines is a key issue for the Hunter," she said.

"A lot of people living here are concerned about how mines are being managed now and what they will look like in the future when mining is finished.

"The proof is in the pudding and this shows the community has good reason to be concerned."

The five Hunter mines were issued with directions by the Resources Regulator to improve operations.

Yancoal's Mt Thorley Warkworth was ordered to engage an independent expert to assess the adequacy of the mine's rehabilitation progress and provide a timeline for works.

Muswellbrook Coal must prepare a mine rehabilitation risk assessment and revise its cost estimates.

Glencore's Ravensworth Operations was instructed to backfill and repair scours and gullies to a section of the mine.

Both Rix's Creek mines were ordered to address risks to ensure satisfactory rehabilitation progress.

Ms Smiles said Bloomfield Group was seeking an expansion of its Rix's Creek open cut mine near Singleton to 2038, despite the fact that it was failing to comply with rehabilitation requirements.

"How meaningful are the conditions of approval when this demonstrates mines are not complying," she said. "There needs to be harsher penalties for mines that do not comply."

Muswellbrook Mayor Martin Rush said while some mines, including Glencore's Mangoola, are "unquestionably best practice" when it comes to rehabilitation, others were dragging the chain.

He said council had considerable concern about the rehabilitation of the old Drayton site, Liddell, Mt Arthur and Bengalla mines.

Resources Regulator executive director Anthony Keon said while some mines failed to comply, overall standards were high.

"The majority of mines inspected displayed a high level of compliance and so the community can have confidence that most operators are meeting their rehabilitation and work, health and safety obligations," he said.

Ms Woods said it was "vital" rehabilitation was done to the highest standard to minimise the risk it would be "left half finished or worse".