The Advertising Standards Authority is investigating whether Royal-Dutch Shell advertisements about hydraulic fracturing are misleading and untruthful, the Treasure Karoo Action Group (TKAG) said on Wednesday.

Shell had run the full-page advertisements in national weekly newspapers and had distributed flyers at its service stations, TKAG national co-ordinator Jonathan Deal said in a statement.

This, after the Cabinet declared a moratorium on all applications for licences to conduct hydraulic fracturing in the exploration of shale gas reserves in the Karoo.

Fracturing, also known as fracking, involves pumping a high pressure mixture of water, sand and chemicals into the shale bed to break apart underground shale rock and extract the gas.

In a live debate with Deal in Cape Town, Shell SA Energy Limited's chairman and vice president Bonang Mohale said there had never been “a single case of groundwater contamination resulting from fracturing”.

“This is clearly not the truth,” Deal said.

He said Shell claimed on its website that: “The fluids injected into the rock consist of more than 99 percent water and sand, with a small amount of additives similar to those found in household products.”

In its advertisement, Shell said: “We also commit to disclosing fracturing fluids at each drilling location.”

However, in the public debate, Shell would not reveal what those chemicals were, Deal said.

“The violations of environmental regulations by Shell, the self-proclaimed market leader in hydraulic fracturing, are a matter of fact,” he said.

“... No reasonable person can possibly argue that hydraulic fracturing is safe and poses no risk to the environment.

“Shell has been economical with the truth. South Africa has been misled.”

Shell was not immediately available for comment.

Proposals have been made by Shell, Falcon Oil and Bundu Oil and Gas to explore shale gas deposits in the Karoo.

However, after pressure from environmentalists, farmers, scientists and citizens, Mineral Resources Minister Susan Shabangu placed a freeze on applications for rights to explore for shale gas until her department has formulated a policy.

Many argued that fracking would impact negatively on ground water and surface water resources in the Karoo.

Last month, French legislators voted to ban fracking and while a study published in the United States found no sign that fracking chemicals were polluting the water supply, it found evidence that gas leaked from shale wells into drinking water. - Sapa