CHEMICALS likely to be discharged by an oil rig drilling in Poole Bay are not a "significant" risk to the environment, the Government says.

The Department for Business, Energy and Industrial Strategy said: "All chemicals used during offshore oil and gas operations undergo stringent safety and environmental risk assessments.

"The risk assessment for the Colter well confirmed that proposed chemical use and discharge would not pose a significant environmental risk."

After several days of delays the rig is now expected to appear in the bay – some four miles from the coast of Studland and six from Bournemouth – over the weekend.

Petroleum licence operator Corallian Energy has until February 28 to assess the level of oil in the Colter prospect, which it expects to take three weeks.