Britain's Civil Aviation Authority (CAA) said on Friday both countries intended to lift national restrictions that remained in place after European authorities declared the helicopters safe to fly last October.

Europe grounded the H225LP and AS332L2 helicopters, built by Airbus Helicopters, after 13 passengers and crew were killed when the rotors flew off their aircraft in April last year.

The decision to extend the safety clearance to Britain and Norway follows "extensive investigation, testing and changes to the helicopter and its maintenance," the CAA said in a statement.

Flights will not resume immediately, however. 

"A plan of checks, modifications and inspections needs to be undertaken before any flights take place," the CAA said.

"It will also be for operators and their customers to decide whether they wish to re-introduce the helicopters to service"

Norwegian oil company Statoil said in December it would stop using H225 Super Puma helicopters for good.

(Reporting by Tim Hepher; Editing by Mark Potter)