A UK review by the Royal Society and the Royal Academy of Engineering has concluded that fracking can be undertaken safely, as long as "best practices are implemented and robustly enforced through regulation."

Fracking (short for hydraulic fracturing) is a process where highly-pressurized liquid is fired into the ground, splintering rocks many hundreds of metres below the surface. Oil and gas escapes, which is then collected up for fuel.

"There has been much speculation around the safety of shale gas extraction following examples of poor practice in the US," said Robert Mair, chair of the review's working group. "We found that the most common areas of concern, such as the causation of earthquakes with any significant impact or fractures reaching and contaminating drinking water, were very low risk."

Those findings are in line with previous reports. The US National Research Council found that earthquakes caused by fracking are rarely strong enough for people to feel. The British Geological survey said it was "extremely unlikely" that groundwater could be contaminated by the process.

The review also points out that open ponds for storing wastewater, which have been used in American fracking operations, carry a possible risk of leakage, but are not permitted in the UK.

One cause for concern is the integrity of wells, as poor cementation and casing failures can lead to leaks and environmental contamination. "Therefore, the review concludes that the priority must be to ensure the integrity of every well throughout its lifetime." Strict well inspections and integrity tests are standard practice are recommended.

The review also recommends providing additional resources as needed to UK regulators, enforcing Environmental Risk Assessments for all shale gas operations, and the robust monitoring of methane in groundwater, seismicity and methane leakages.

Mair adds, "this review is not an exhaustive analysis of all the issues associated with shale gas and we have highlighted a number of issues that we believe merit further consideration, including the climate risks associated with the extraction and subsequent use of shale gas, and the public acceptability of hydraulic fracturing."