A South African environmental group renewed its call for a moratorium on shale-gas fracking, as the government moves closer to a decision on whether to allow the process opponents say imperils water quality.

The Treasure Karoo Action Group, named after the semi-desert area of South Africa that has attracted petroleum exploration companies, started in Johannesburg the latest phase of a campaign to block the drilling technique.

An April 2011 moratorium placed on shale-gas exploration in South Africa ended in September 2012. The government on Oct. 16 published proposed regulations for hydraulic fracturing as it seeks to tap as much as 390 trillion cubic feet of resources in the Karoo. Opponents of fracking, which blasts water, chemicals and sand into rock to release natural gas, say it risks contaminating ground water.

Royal Dutch Shell Plc is among explorers to have applied for permits to explore the Karoo. South Africa, which imports 70% of its crude-oil needs, estimates shale gas may generate 1 trillion rand ($100 billion) of sales within three decades, helping to bring it closer to self sufficiency.

Energy Minister Tina Joemat-Pettersson said the development of shale gas “can’t be dismissed,” according to a transcript of a speech yesterday. “Our government has adopted a cautious and responsible approach that seeks to understand the risks to the environment posed by fracking.”