The 450-mile (725km) cable connects Blyth in Northumberland with the Norwegian village of Kvilldal.

At full 1,400 megawatt capacity it will import enough hydro-power to supply 1.4 million homes, National Grid said.

National Grid Ventures president Cordi O'Hara said it was a "remarkable feat of engineering".

She added: "We had to go through mountains, fjords and across the North Sea to make this happen.

"North Sea Link (NSL) is also a great example of two countries working together to maximise their renewable energy resources for mutual benefit."

National Grid said the €1.6bn (£1.37bn) joint venture with Norwegian power operator Statnett would help the UK reduce carbon emissions by 23 million tonnes by 2030.

It has four other power cables running to Belgium, France and the Netherlands and said 90% of energy imported in this way would be from zero carbon sources by 2030.

Hydropower in Norway and wind power in the UK are subject to weather conditions and fluctuations in demand.

Using NSL, renewable power can be exported from the UK when wind generation is high and electricity demand low, or be imported from Norway when demand is high and wind generation low.

Business, Energy and Industrial Strategy minister Greg Hands said NSL enabled both countries to "benefit from the flexibility and energy security that interconnectors provide".

He added: "This pioneering partnership shows first-hand how crucial international cooperation will be in helping us to deliver on our net zero ambitions."

The cable will allow the UK to swap wind energy for Norway's hydropower