The Preston New Road site with the two gas flare stacks in the bottom right corner

The release of unburned methane, a greenhouse gas, occurred when Cuadrilla was flow testing gas released from shale rocks after it fracked late last year.

The EA estimated between 2.7 and 6.8 tonnes of methane were sent unburned through the flare stacks at the site but said that although it breached its permit it was no risk to people and had “minimal to no impact on the environment”.

But a spokesman from Frack Free Lancashire said: “Cuadrilla’s Preston New Road ‘flagship’ site was peddled as the most monitored site in the UK. Cold-venting methane is another in the history of breaches against their key environmental permits.

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“The community has been given repeated assurances about the “gold-standard, robust regulations” but this clearly shows that Cuadrilla cannot be trusted to operate safely and within the rules. It’s very concerning.”

Nick Mace from Cuadrilla said: “We are fully committed to delivering our shale exploration operations in a safe and environmentally responsible way as a top priority and have amply demonstrated how we do this on a day to day basis.

"The impact of the non-compliance is considered minor, with minimal to no impact on the environment. Cuadrilla will work will the Environment Agency to proceduralise this approach for future operations. Local people can be reassured that Preston New Road is the most monitored site in Europe and we continue to work closely with a range of regulators each and every day.”

Fylde MP Mark Menzies said: “While any breaches of regulations are unacceptable, I am pleased to see the regulatory framework working.