NETWORKS of tunnels connecting Scotland’s islands are being “seriously thought about” as an option to bring more sustainable travel to the communities, a UK minister has said.

Scotland Office minister Iain Stewart said that the Faroe Islands, which opened the world's first undersea roundabout and where he has led a “fact-finding” mission, show what is possible.

However, the Scottish Government has emphasised that “transport is devolved” and outwith the remit of Tory ministers.

Stewart, a minister in the Scotland Office despite being the MP for Milton Keynes South, said the idea of tunnels connecting islands was “worth exploring”.

READ MORE: Tunnels to replace ferries and a Clyde Metro map – here's what's in the Scottish transport review

Longer links, such as between Orkney and Shetland, are likely unfeasible, but fixed tunnels connecting islands within each chain, and over in the Western Isles, is being touted as a possibility.

Stewart said: "I've got an open mind – it may not be practical, but given the population sizes are broadly comparable, it seems worth exploring.

"Particularly when you look at the wider cost-benefit analysis in terms of social issues, stopping depopulation, improving healthcare, decarbonisation."

He added: "It's not going to be cheap, but you contrast that against building several new ferries – not just once, but given those tunnels would be there for many, many years, probably two or three cycles of building ferries."

The Tory minister (below) said the tunnels in the Faroe Islands cost about £20 million per kilometre.

The National:

Sigurd Lamhauge, chief executive of Landsverk, the organisation which oversees transport projects on the Faroes, said: “The system of tunnels we have built in the Faroes has led to increased incomes, improved access to healthcare and education, better commuting times and resulted in more people staying on the islands.

“They have brought positive change to the Faroes and I would think something similar would have the potential to do the same to places like Orkney, Shetland and other Scottish islands.”

As part of its Transport Review released in January, the Scottish Government said that some ferry links could be replaced with tunnels or bridges, including at the Sound of Harris, the Sound of Barra, and between Craignure on Mull and Oban on the Scottish mainland.

Na h-Eileanan an Iar MP Angus MacNeil said that tunnels were the "obvious solution", and said ferries should no longer be used for shorter routes.

He told The National: "I am glad to see Tory ministers eventually joining this call for tunnels - it is the obvious solution and has been obvious for years. It is so obvious that the Faroese have four undersea tunnels between 6km and 11km in length.

"Scotland has to catch up. We should not routinely build ferries for sea routes of lengths less than 11km anymore - it should automatically be a tunnel, which wouldn't need to be replaced every couple of decades."

A spokesperson for SNP transport minister Jenny Gilruth said: “If Mr Stewart is interested in sharing any of the facts he has gathered from his trip, the Scottish Government would be more than willing to hear them, recognising, as Mr Stewart will of course respect, that transport is devolved.”