Eircom UK Limited is suing BT over the tendering of the Northern Ireland Public Sector Shared Network contract. Photo: Hollie Adams/Bloomberg

Eircom UK Limited is suing BT over the tendering of the Northern Ireland Public Sector Shared Network contract. Photo: Hollie Adams/Bloomberg

A telecommunications company lost millions of pounds of profit due to “unlawful conduct” by BT in a contract battle, the English High Court has been told, in what is claimed to be one of the first cases of its kind to be heard in British courts.

Eircom UK Limited, part of the Eir group, is suing BT over the tendering of the Northern Ireland Public Sector Shared Network contract (NIPSSN), which was awarded to BT in 2018 and is worth up to £400m.