Anger at BT’s failure to commit to a large-scale broadband network upgrade has triggered a new discussion of whether it should be forced to spin off its network subsidiary Openreach.

Ministers and regulators are understood to be “extremely frustrated” by an announcement this month that only three million homes on the national telecoms network will get a “full fibre” connection by 2020. The investment was announced after months of industry consultation by Openreach and comes as much smaller infrastructure rivals make bigger plans.

Westminster sources said that the Department for Culture is now preparing to revisit the question of a full split of BT as part of an ongoing review of future telecoms infrastructure.