The British government came out in favour of a controversial shale gas extraction method known as fracking, saying on Thursday that work should be resumed even though it is suspected of having triggered earthquakes.

Exploratory fracking can restart under tight controls to "mitigate the risks of seismic activity", Energy Secretary Edward Davey said in a statement.

The British energy firm Cuadrilla Resources had been forced to halt drilling trials in Lancashire in northwest England after the technique was thought to have caused a 2.3-magnitude tremor in April 2011 and a 1.5-magnitude tremor in May.

But Davey said on Thursday that his decision to allow the firm to resume test drilling was "based on the evidence".

"It comes after detailed study of the latest scientific research available and advice from leading experts in the field," he said.

"We are strengthening the stringent regime already in place with new controls around seismic risks.

"And as the industry develops we will remain vigilant to all emerging evidence to ensure fracking is safe and the local environment is protected."

Davey said shale gas was a "promising new potential energy resource" for Britain which could contribute to energy security and reduce the reliance on imported gas.

Hydraulic fracturing or fracking is the drilling of underground shale rock formations by injecting chemicals and water to release trapped natural gas.

Opponents say it causes water pollution but energy groups say it provides access to considerable gas reserves and drives down prices.

Cuadrilla Resources' chief executive Francis Egan hailed the decision as said "a turning point for the country's energy future".

"Shale gas has the potential to create jobs, generate tax revenues, reduce our reliance on imported gas, and improve our balance of payments," he added.

Exploitation of shale gas in the United States has helped to substantially bring down energy prices and the British government has expressed hope that it can have a similar effect in Britain.

Davey warned though that Britain should not put all its hopes in shale gas extracted through fracking, and it must be part of a mix of energy sources.

"We shouldn't bet the farm on shale gas," he said.

"I am absolutely clear that the most responsible and sensible way forward for energy policy is to have a diverse set of sources."

Cuadrilla is the only company which has currently started exploration of shale gas resources in Britain, but the government's decision clears the way for potential exploration elsewhere.

The company says reserves in Lancashire alone could supply a quarter of Britain's gas demands in the future.

Other areas where fracking for shale has been mooted include in West Sussex, where concerns have been voiced about pollution of water supplies, and in the Mendips, raising fears it could affect the renowned hot springs at Bath.

Friends of the Earth Executive Director Andy Atkins, said: "Giving the green light to fracking for shale gas will send shock waves across the UK.

"Communities up and down the country will be disturbed by this reckless decision which threatens to contaminate our air and water and undermine national climate targets."