The Government agency in charge of regulating the UK's oil and gas says it will not review the fracking earth tremor limit despite calls from a Lancashire energy firm to do so.
The response came only an hour after Lancashire energy firm Cuadrilla announced it has asked the Oil and Gas Authority "urgently review" the traffic light system (TLS) used to monitor fracking.
The company has paused fracking at its Preston New Road site since December last year.
Under the TLS fracking must be stopped if earth tremors of more than 0.5 magnitude (ML) are recorded.
Speaking after Cuadrilla's announcement, a spokesman from the Oil and Gas Authority said: "There are no plans to review the limit under the traffic light system."
Cuadrilla said that "an intentionally conservative micro-seismic operating limit" of 0.5ML had "severely constrained the volume of sand that could be injected into the shale rock".
It added: "Cuadrilla has now shut in the well and will monitor build-up as it continues to assess the results."
Cuadrilla and energy giant Ineos, another company planning to frack for shale, have both called for a review of the tremor limits set by the Government but energy minister Claire Perry has indicated there are no plans to alter the rules.