Owned by Norway’s Statnett and the UK’s National Grid, NSN is a 740km electricity link that enables transmission of renewable energy between the two countries.

The link, which is scheduled to be operational by 2021, will have electricity supplied through high-voltage onshore and offshore cables from Kvilldal in Norway to Blyth in the UK.

The current contracts awarded by NSN include more than €1bn cable supplies by Prysmian and Nexans. The two companies will supply a 730km subsea HVDC system and 10km onshore cables.

Statnett executive vice-president Håkon Borgen said: "This project is an important part of Europe’s future electricity system and we are very pleased to have these contractors aboard. Now we can go further in building the world’s longest interconnector."

Prysmian will supply and install 950km of submarine and land cables for the UK and Norwegian North Sea sections of the route, while Nexans will supply the fjord, tunnel and lake sections, and the onshore connection in Norway, Statnett said.

Whereas Prysmian will manufacture its cables in Naples, Italy, Nexans will produce them at its Halden plant in Norway.

The cables will be laid by the vessels Giulio Verne and C/S Nexans Skagerrak of Prysmian and Nexans, respectively.

NSN has also awarded a €408m ($450m) contract to ABB to supply converter stations in the UK and Norway.

National Grid European business development director Alan Foster said: "There is a huge program of work for us to undertake over the next five years to deliver what will be the world’s longest interconnector.

"Our contractors will have a big part to play in that successful delivery. But the benefits to both UK and Norway are also huge and when completed the link will deliver low carbon electricity for the UK and also add to security of supply for Norwegian consumers."