The feasibility of building a bridge or tunnel between Northern Ireland and Scotland is to be examined as part of a review of transport connections across the UK.
Downing Street said on Saturday the review, led by Network Rail chair Sir Peter Hendy, will explore the "cost, practicality and demand" for a fixed link, which some critics have already dismissed as impractical and a waste of money.
British prime minister Boris Johnson has mooted the bridge idea several times and the government confirmed earlier this year that it was being discussed by officials.
The transport study will set out advice on a “wide range of possible options” to improve the quality and availability of links across the UK, Downing Street said.
The review comes after Mr Johnson, in a speech in July on how to kick-start the British economy following the coronavirus pandemic, pledged £100 million (€110m) on 29 road projects.
Downing St said the Hendy review will also look at the feasibility of various other options designed to boost links to Scotland and Wales, including improving major roads like the A1.
Making the review announcement on Saturday, Mr Johnson said: "The United Kingdom is the greatest political partnership the world has ever seen and we need transport links between our nations that are as strong as our historic bonds."
Sir Peter, who ran London's transport network during the Olympics in 2012, said: "Improving links across the UK on the basis of the wider economic benefits that increased investment will deliver will be of benefit to everyone in the UK, and I'm thus very pleased to lead this work."
He is expected to publish his recommendations next summer.
Politicians from Scotland and Northern Ireland told Transport Secretary Grant Shapps in March that the billions of pounds a fixed link across the Irish Sea would cost could be better spent on vital infrastructure projects. - PA