More than 100 climate activists have gathered to demand the proposed extension of Hunter Valley Operations (HVO) mine near Singleton be scrapped.
The state government is considering approving an extension of the mine, which has been described as the state's "largest coal mining proposal ever".
If approved, extension would extend mining to 2050 and generate an estimated 1.2 billion tonnes of lifetime emissions.
The NSW Environment Protection Authority has said the proposal could make it harder for NSW to meet its legislated emissions reduction targets.
"It's outrageous that the NSW government is considering approving the largest ever coal project in the state's history when they're not on track to meet their own climate targets," Rising Tide spokesman Zack Schofield said.
"The chief executive of the Port of Newcastle has said the coal export market could die within the decade, so massive new coal projects do nothing for the Hunter except pour fuel on the climate fire. Minns needs to rule out new coal and focus on supporting Hunter workers to the industries of the future".
HVO general manager Dave Foster recently questioned the EPA's assessment of the mine's share of NSW greenhouse gas emissions.
He said the proposal would be to continue mining largely in already approved areas with little additional disturbance and no increase to annual production volumes.
"Continued mining at HVO will provide the community with an economic and social anchor as we move to a lower-carbon future," he said.
Monday's meeting, held at Stevenson Park, Mayfield, was organised by Newcastle-based climate group Rising Tide, which blockaded the Newcastle coal port for more than 30 hours in November 2023.
Ex-Hunter coal miner and grandparent Ian Hodgson said he was willing to take action to protect his grandchildren.
"The last thing we need in the Hunter is more coal. I've had opportunities that young people will never have because the climate crisis will increasingly disrupt every element of our lives," he said.
"If our government chooses to invest in coal exports instead of renewables when our main trading partners are rapidly decarbonising, we'll be left high and dry with unemployment, stranded assets, and a climate crisis."
