Boris Johnson has described the idea of a bridge connecting Scotland and Northern Ireland as “very interesting,” after reportedly seeking out cost estimates for the project.

The Prime Minister was responding to a question in the House of Commons over a ‘Boris Bridge” across the Irish Sea - three months after asking Treasury officials to prepare a report on the potential benefits and risks of the plan.

Mr Johnson previously claimed such a project would cost around £15 billion to complete and once floated the idea during his time as foreign secretary.

READ MORE: Boris Johnson seeks cost estimates for a Scotland-Northern Ireland bridge

However, the report, leaked to Channel 4 in September, said it was not without danger, citing particular concern around the presence of WW2 munitions in the Irish Sea.

A road connection between the two countries has been championed by the DUP, who said it would encourage economic growth and recognise "the strong economic, cultural and social links between the two regions".

In was first put forward in the party's 2015 election manifesto, but has grown in potential significance since the 2016 Brexit vote. 

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Speaking in the Commons on Thursday, Mr Johnson answered a question from Northern Irish MP Ian Paisley Jr, who asked if Johnson would consider “building a Boris bridge, not just a Boris bus.”

The Prime Minister responded: “As for the desire for a bridge to connect the two biggest isles in the British isles, all I can say is that it is a very interesting idea.”

“I advise him to watch this space and indeed, watch that space between those islands because what he has said has not fallen on deaf ears.”