The UK Government has so far failed to hold any formal discussions with Holyrood over a fixed link between Scotland and Northern Ireland, despite one minister claiming they were "committed in principle" to the idea.
Boris Johnson has enthusiastically backed a bridge or tunnel one day stretching across the North Channel to link Portpatrick and Larne, but the SNP has dismissed it as a "vanity project".
Tory ministers have established a "Union Connectivity Review" to establish whether such a crossing is realistic, despite transport being a matter devolved to the Scottish Parliament.
Transport Scotland, the quango which usually manages major road and rail developments north of the Border, told the Record it had no formal contact over a fixed link to Northern Ireland and no input to the business case.
A spokesman said: "Transport infrastructure is a devolved matter and the Union Connectivity Review was established without any meaningful discussion with devolved administrations.
"We seek to engage constructively with the UK Government, however, not in a way that undermines the devolution settlement.
“Transport infrastructure investment should focus on projects that improve lives, boost our economy, support communities and work towards Net Zero.
"That is how we are planning Scotland’s future transport infrastructure investment through the second Strategic Transport Projects Review.”
In an interview with the Sunday Times last month, Northern Irish secretary Brandon Lewis said: "I think it is a really good idea.
"It would also be good for Ireland to have that physical connection to the UK market. Experts are looking at the business case but as a matter of principle I'm right behind it."
Scottish transport secretary Michael Matheson has previously dismissed the prospect of such a tunnel or bridge ever being built in his lifetime.
"It's not a priority for the Scottish Government and it's not a priority for the Northern Irish Executive. Nichola Mallon, the Northern Irish infrastructure minister, has made that very clear," he told the Record in March.
"The reason why it's not a priority is it runs the danger of drawing financial resource away from other critical elements of infrastructure - such as schools, health housing, and other transport priorities - all because the UK Government has set themselves on this course of wanting to invest in a tunnel or a bridge to Northern Ireland."
Asked if it was realistic to build a fixed link across the North Channel, Matheson continued: "Even if something is feasible, it doesn't mean you should do it.
"I suspect the complexities and the challenges associated with some form of fixed link are such that it probably won't happen in my lifetime. And I suspect it won't happen in Boris Johnson's lifetime."
