LONDON -- BT is laying a new fibre optic submarine cable between Orkney and the Scottish mainland to help bring its 21st Century Network to the Northern Isles.

The 70 km cable will run from Skaill Bay in Orkney under the Pentland Firth to Dunnet Bay, around five miles east of Thurso.

BT has awarded the contract to independent marine engineering company Global Marine Systems Ltd. (Global Marine), who began installing the cable on Wednesday. Weather permitting, the work should be completed in around three weeks.

Global Marine’s cableship CS Sovereign is using its submersible plough and remotely operated vehicle systems to install the cable up to one metre below the seabed.

The new cable is the latest step towards bringing BT’s 21 Century Network – the world’s most radical next generation communications transformation programme – to the islands.

BT has already reached agreement with Faroese Telecom to share part of a new fibre optic submarine cable which has been laid between the Faroe Islands, Orkney and Shetland and the Scottish mainland.

The cable, which comes ashore at Banff, will provide connectivity to the Northern Isles alongside existing microwave radio links.

BT Group plc (NYSE: BT; London: BTA)