Fracking could return to the UK if firms find a way to reduce the earthquakes it causes, the chief executive of Britain's oil and gas regulator has revealed.
Fears have grown about energy security following Russia's invasion of Ukraine.
Hydraulic fracturing, or fracking, is a controversial technique designed to recover gas and oil from shale rock.
But, though fracking could resume south of the border at some point in the future, the Scottish Government does not support unconventional oil and gas development.
Andy Samuel, who leads the Oil and Gas Authority (OGA), told The Telegraph that at least one firm is hoping to resume fracking with new techniques that could avoid tremors of above 0.5 on the Richter scale - the current limit.
A 2019 UK moratorium on existing fracking methods has led to sites being filled in with concrete and concern that Britain's underground gas reserves may never be extracted for fuel.
The regulator is under pressure to reverse an order to fill in two fracking wells in Lancashire, with MPs arguing that the sites have not reached the end of their useful life and could be used to improve the UK's energy security.
Concerns
Fracking is unpopular with the public and has prompted safety concerns over damage to buildings and water pollution.
But Mr Samuel suggested the technique could return in years to come.
"We've left the door open to industry, and one operator is wanting to kind of progress the science, and try and understand if there is a way that it could be done without exceeding the seismic event limits," he said.
UK Ministers have not ruled out the prospect of more fracking in the future if they are presented with evidence that tremors can be kept to a minimum. However, they have been keen to stress that they have no plans to lift the fracking moratorium, and that any new developments would take at least a decade to set up.
Mr Samuel was sceptical about the possibility of new methods for tremor-free extraction being developed soon.
MPs have questioned the decision to set the limit for tremors at 0.5 on the Richter scale - four times lower than the limit in the US.
An OGA report found that, at worst, the tremors had caused "slight non-structural" damage to buildings near a fracking site.
Scottish Government position
A Whitehall source said: "We ended support for fracking because it is not currently possible to accurately predict the probability and severity of earthquakes associated with the process.
"It remains our position that fracking will not be allowed to proceed unless compelling new scientific evidence on its safety is provided."
At the end of 2019, the Scottish Government set out a finalised policy of no support for unconventional oil and gas (UOG) development, which includes fracking.
The then Energy Minister Paul Wheelhouse confirmed this position following evidence-gathering and consultation, including environmental and business assessments.
He also set out the factors which led to this decision, including the incompatibility of UOG development with climate-change policy.
The Scottish Government said it will not issue licences for new UOG development, and that Scotland's planning framework will not support development using UOG extraction techniques.