Plans by energy companies to prospect for shale gas in the Karoo are flawed, anti-fracking lobbyists Treasure Karoo Action Group (TKAG) said on Monday.
"Our research, as well as a legal-scientific review of the environmental management plans of the three current applicants... has revealed fatal flaws," the group said in a statement released at a media briefing in Cape Town.
The briefing comes three days after the government's decision to lift a moratorium on exploring for shale gas in the Karoo, using the controversial method of hydraulic fracturing, commonly called fracking.
Among the companies that have made application is oil giant Royal Dutch Shell.
TKAG said the flaws "mean that the plans of the applicants are at odds with various South African laws and regulations, as well as the Constitution of the country".
The group again vowed to take its fight against fracking to the Constitutional Court.
TKAG chairman Jonathan Deal said support, both locally and internationally, for his organisation's opposition to fracking had been pouring in.
"The support we have received locally and internationally since the government lifted the moratorium on fracking... has been overwhelming," he said.
It was clear there was "widespread abhorrence" to fracking.
Deal said hydraulic fracturing had either been banned or restricted in 155 jurisdictions around the world.