A number of protesters have been arrested at Whitehaven Coal mine sites in northern NSW, as activists urge the state government to review how the controversial mines were approved.
Police cracked down on the activists early on Monday morning following a weekend of demonstrations which saw around 170 people turn out to mine sites across the Gunnedah basin.
The Leard Forest Alliance are calling for the controversial Maules Creek mine, which is located in the basin, to be shut down and for a parliamentary inquiry to investigate how it received approval.
"These have been flawed, slimy dealings," the group's spokeswoman Helen War said.
"The whole development process needs to be reassessed."
Activists locked themselves to gates, barrels of concrete and other makeshift structures to blockade roads leading in and out of the mines.
Police have confirmed that at least four protesters were arrested and charged.
Ms War claims two female librarians were detained, as well as 93-year-old war veteran Bill Ryan and his son Colin Ryan, who locked themselves to gates at the Werris Creek development.
"(At the Gunnedah site) hundreds of workers have been unable to get in and access the machinery and there are 30 trucks waiting on the side of the road," she told AAP.
But Whitehaven Coal managing director Paul Flynn disputed those claims and denied the company's operations had been significantly disrupted.
"(The cost) won't be material for us," he told ABC Radio.
"There will only be a marginal impact on us for the day."
Acting NSW Resources and Energy Minister Kevin Humphries condemned the actions of a "small band of imported professional protesters" who he said don't representative the local community.
"The community understands the importance of these projects and the enormous economic benefit they will provide to the region and to the state's economy," he said in a statement.