Officials are actively studying Boris Johnson's plan for a new bridge between Scotland and Northern Ireland, it has emerged.
The prime minister last year threw his weight behind proposals for a £15bn link between mainland Britain and Northern Ireland, with sources close to the then-foreign secretary saying it was "the kind of ambitious project we need to make a success of Global Britain".
Documents obtained by Channel 4 News show that both the Treasury and Department for Transport have now been asked to look into the costs and risks of such a bridge.
According to the broadcaster, the DfT has drawn up a “factual paper on the subject” following conversations between the DUP and former transport secretary Chris Grayling.
Johnson reportedly wants to find out where the money for the project could come from, as well as "the risks around the project" – which apparently include "WW2 munitions in the Irish Sea". He had previously called for a similar bridge to be built across the English Channel in a bid to bring France and England closer together after Brexit.
A government spokesperson said: "Government regularly commissions work to examine the feasibility of projects. During the leadership campaign candidates spoke about a number of issues which resulted in Number 10 commissions ahead of a new prime minister taking over.
"This PM has made no secret of his support for infrastructure projects that increase connectivity for people and particularly those that strengthen the Union."
A new link between Northern Ireland and mainland Britain has previously been talked up by the DUP as a way of potentially breaking the Brexit impasse over the Irish backstop, which is intended to avoid a hard border on the island of Ireland but which has been rejected by MPs as part of the withdrawal agreement.
It is also not the first time that the prime minister has proposed construction of a new bridge. He backed the development of a so-called Garden Bridge in London when he was mayor in the capital, but the scheme was cancelled after the estimated cost of the project had increased from an estimated £60m to around £200m.