The US Federal government has given Royal Dutch Shell a final permit to search for oil under the floor of the Arctic Ocean – an activity it has been banned from carrying out for two decades.
The Anglo-Dutch oil and gas company has already been drilling in the area just off the northwest coast of Alaska for a month, but until now it has been limited to drilling into the top sections of two wells.
The Bureau of Safety and Environmental Enforcement (BSEE) decided to approve the permit after Shell repaired a key piece of equipment, which in its former state could have caused a well blow-out.
The area is rich with opportunities for firms searching for oil – scientists have estimated that over 20 per cent of the world's undiscovered oil and gas is based in the Arctic, and Shell has already invested around $7bn (£4.5bn) in the project.
But the plan has faced still opposition from environmental activists, who say drilling there will cause damage to the wildlife and habitat.
In a statement, the BSEE said it would monitor Shell's activities closely to ensure environmental standards were met.
"Activities conducted offshore Alaska are being held to the highest safety, environmental protection, and emergency response standards," said agency director Brian Salerno.
We will continue to monitor their work around the clock to ensure the utmost safety and environmental stewardship.