Fracking, the controversial process of extracting gas from rock deep underground, has come under intense scrutiny internationally due to growing concerns about health and environmental pollution.

It has been suspended or banned in some countries, including France and parts of the US and Britain, where it has been blamed for causing earthquakes.

Fracking involves forcing up to 10 million gallons of fluid up to 1,000 metres below the surface to crack open the rock formation.

The gas found in the shale below the rocks is then channelled back to an onshore well.

Pollution can occur if seals break in the underground vertical pipeline, which runs through aquifers and other water supplies.

A 'New York Times' investigation found the waste water in some such wells contained dangerously high levels of radioactivity.

It was being sent to treatment plants not designed to deal with it or discharged into rivers that supply drinking water.

An award-winning 2009 film, 'Gasland', exposed the health ill-effects suffered by many US residents living near gas wells, the destruction of landscape, and instances of water, soil and air pollution.

Many of the harmful effects associated with fracking are caused by the toxic make-up of the frack fluid, which can contaminate groundwater.

Tamboran, the Australian company behind the first such project here, insists it won't use chemicals.

A US EPA study found contaminants in drinking water, including arsenic and copper, adjacent to drilling operations.

Paul Hetzler, a former official with the New York Department for Environmental Conservation, warned that fracking posed a risk to drinking water supplies.

"When contamination occurs -- and it will occur -- we will all pay for it, regardless of where we live," he said.