Activists are challenging a permit given to a fracking site in Lancashire in the latest legal test for the controversial fossil fuel extraction technique.

Friends of the Earth say the Environment Agency (EA) has failed in its duty to promote the use of the “best available techniques” to reduce the environmental impact of fracking.

They are launching a challenge in the High Court against the permission granted for oil and gas exploration company Cuadrilla to drill at their Preston New Road site.

Specifically, they argue that the EA should have considered the use of other techniques that produce less contaminated waste fluids when it considered Cuadrilla’s application in 2017.

Tony Bosworth, Friends of the Earth campaigner, said: “All along, the government stated that gold standard regulation would make fracking OK, but we believe our case, and the reality of what’s happening at Preston New Road, shows the opposite.

“They should be putting in place the best possible regulation to ensure that people, and the environment are protected.

“How can the government be considering rolling fracking out across the country, when it can’t be properly regulated at even one site? Isn’t it time the government gives up on fracking and backs renewables instead.”

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“Flowback fluid” is produced at fracking sites after water is pumped into cracks in the rock to extract shale gas, and the liquid must be either reused or removed and processed at special facilities.

The campaigners say the EA should have considered a technique called “electrocoagulation”, which they say could produce cleaner fluid, before granting permission at the site.

Fracking at Preston New Road started in mid-October. It has since been a target for protesters and has been forced to halt drilling repeatedly after earth tremors at the site exceeded legal limits.

There have already been two unsuccessful attempts by protest groups to stop their operations.