A CONTROVERSIAL plan to build a bridge or tunnel between Northern Ireland and Scotland is to be examined as part of a national review of UK transport connections.

Downing Street yesterday announced the “cost, practicality and demand” for a fixed link would be explored as part of a review led by Network Rail chair Sir Peter Hendy.

However critics have already dismissed the proposal – which has been mooted several times by Boris Johnson – as impractical and a waste of money.

The cost for a bridge has been estimated as at £20billion, with concerns the final sum could spiral due to the infrastructure which would be needed on either side.

One expert previously described it as “about as feasible as building a bridge to the moon”.

Scotland’s transport minister has also criticised a lack of consultation over the review – despite transport being a devolved issue.

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.

It 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.

READ MORE: Chinese media bemused over 'Boris Bridge' controversy, architect says

Making the review announcement, 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.”

Hendy, 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 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.

However Scotland’s Transport Secretary Michael Matheson said the Hendy review has been “organised with virtually no consultation”, despite transport being a devolved issue.

He said: “We absolutely want to see improved transport and connectivity links beyond Scotland’s borders – under any constitutional arrangements.

“But this study is clearly part of the Tory Government’s wider agenda to undermine the devolution settlement across a whole range of policy areas.”

Johnson first suggested the idea of a bridge across the Irish Sea when he was foreign secretary in 2018.

At that time, James Duncan, a retired offshore engineer from Edinburgh, said the idea was “about as feasible as building a bridge to the Moon”.

“Many long bridges have been built, but none across such a wide, deep and stormy stretch of water,” he wrote in a letter to the Sunday Times.

Concerns have been raised over any transport link having to avoid Beaufort’s Dyke, where tonnes of weapons were dumped in the sea between Scotland and Northern Ireland following the Second World War.

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.

Johnson championed a plan to build a bridge covered with trees and flowers over the River Thames in London when he was Mayor of London – which was subsequently cancelled and ended up costing the public purse £43 million.