A major transport connectivity review is assessing the feasibility of a bridge or tunnel between Northern Ireland and Scotland.
The research is being carried out as part of British prime minister Boris Johnson’s bid to improve transport links.
Peter Hendy, who is carrying out a review of connectivity across the UK, said further work is required on the possibility of a “fixed link” across the Irish Sea.
Mr Hendy has commissioned two engineering professors to lead a study into the feasibility of a bridge or tunnel between Northern Ireland and Scotland, outlining its cost, timescale and the work involved.
Mr Johnson has repeatedly spoken about the prospect of a bridge, even though experts have warned that the depth of the Irish Sea and the presence of dumped munitions would cause problems.
The scheme could cost a reported £20 billion (€23 billion), although Mr Johnson has previously said it would “only cost about £15 billion”.
The distance from Larne to Portpatrick, one of the most likely routes for a bridge, is around 28 miles (45km).
There is no problem with distance, money or the Beaufort’s Dyke explosives disposal area, according to Mr Johnson.
In November 2018, he said: “The problem is not the undersea Beaufort’s Dyke or lack of funds. The problem is an absence of political will.”
England’s transport secretary Grant Shapps rejected a claim by Scottish first minister Nicola Sturgeon that the money could be better spent elsewhere.
He told the BBC: “I understand that it is not the responsibility of the Scottish first minister to connect the United Kingdom together. The Scottish first minister doesn’t even believe we should be in a United Kingdom. So I understand her perspective but I think it is wrong.
“For example, if you live in Northern Ireland, you want to know that you can reliably get the hauliers and lorry drivers in with goods from the mainland of the British Isles.
“Why would you ever be against connecting different parts of our country in a better way? It shouldn’t be a controversial thought at all.
“As one small part of this Union connectivity review [we will] undertake a study of the feasibility of doing that and we will report back in the summer.”
A proposal for an undersea bridge between Ireland and Scotland was dubbed the “Boris Burrow” by the British press earlier this year, with Stormont’s Minister for Infrastructure, Nicola Mallon, dismissing the idea as “nonsense”.