A British government-appointed panel said Tuesday that a controversial gas extraction method known as fracking should resume under strict conditions, though it would probably trigger earthquakes.

The British energy firm Cuadrilla Resources halted drilling trials on Lancashire's Fylde coast in northwest England after saying they likely caused a 2.3-magnitude tremor in April 2011 and a 1.5-magnitude tremor in May.

But a group of experts commissioned by the energy ministry said that the operations should be allowed to restart under tight controls.

The group added however that an instant shutdown should occur even in the event of a tremor that is too small to be noticed above ground.

"The authors of this report see no reason why Cuadrilla Resources Ltd. should not be allowed to proceed with their shale gas exploration activities and recommend cautious continuation of hydraulic fracture operations at the Preese Hall site," the report said.

There will now be a six-week consultation period with residents and environmental groups, the Department of Energy and Climate Change said.

"No decision has been taken on whether to allow fracking to resume at Cuadrilla's sites in Lancashire," a spokesman said.

Cuadrilla chief executive Mark Miller said he was "pleased that the experts have come to a clear conclusion that it is safe to allow us to resume hydraulic fracturing, following the procedures outlined in the review."

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.

The experts' report agreed with Cuadrilla's assessment that the fracking was to blame for the tremors.

But it said coal mining in Britain had produced similar strength earthquakes and that any further seismic events in the area would be "unlikely to cause structural damage".

The report said the drilling process should be more cautious, with a smaller injection of water and better monitoring.

Any tremor of a magnitude of 0.5 or above should lead to an immediate halt followed by remedial action, it added.

Some US states and other countries have moved to ban certain types of fracking, although the industry contends the techniques have been in use for decades and are safe.