OIL firm Corallian Energy is expected to seek an extension to the time period allowed for its operation in Poole Bay.

The rig ENSCO 72 arrived in the bay at the weekend drawing sightseers to the cliffs of Purbeck and the conurbation, having been delayed for almost a week due to bad weather.

Campaign groups opposed to the drilling have been hoping the firm would be forced to abandon the operation as under its current contract it is required to close the well on February 28.

However the Government has said it expects the firm to seek an extension, which would be reconsidered for any potential environmental impact.

Responding to a query from resident Alistair Keddie of Save Our Shores Bournemouth, the environmental manager at industry regulator OPRED said Corallian's previous drilling operation in Scotland had also been delayed by bad weather, having a knock-on impact.

"We therefore anticipate that when the rig arrives at the Colter location and commences the drilling operations, Fraser Well Management (the rig operator) will reassess their timetable and it may be necessary to submit applications to vary the environmental approvals to extend operations into March.

"Such an extension request would not be abnormal, as drilling operations can often be delayed for a number of reasons, including weather during the winter months.

"Whether we would agree to extend the approvals would depend upon our assessment of the potential environmental impact of the delay and would not necessarily be constrained by the operational window agreed with Corallian during our consideration of the Environmental Statement."

She said the assessment would take into account "comments received from our environmental and navigational consultees and issues such as the breeding seasons of birds and fish (including seahorses)".

Corallian plans to drill an area known as the Colter prospect, some four miles from Studland, to assess the quantity and accessiblity of the oil there. It assesses the chances of success at 58 per cent.

If the appraisal well is successful Corallian says an extraction firm could drill out horizontally from Wytch Farm, eliminating the long-term need for a rig in the bay.

Mr Keddie, in his email to OPRED, pointed out that the winter drilling window of November 1 to February 28 was a 'key mitigation factor' identified by Corallian when applying to drill.

"Given that the rig is unlikely to be fixed in place before February 5, Corallian cannot possibly comply with its current permit deadlines, it’s revised EIA or the Key Mitigation Factor set out in the ES," he said.

"A 38 day window would take them halfway into March, an important month for the breeding of protected species of birds, fish and seahorses.

"We think it is likely that Corallian will move the rig in to place and then apply for an extension to their permits, knowing full well that they cannot meet the existing deadlines.

"As the UK regulator, OPRED have a duty to ensure that Corallian and their partners comply with the clearly stated commitments in their ES and EIA.

"Any extension to their current drilling permits would allow Corallian to ignore a Key Mitigation Factor and break those commitments."