Plans to connect four UK islands via a £500million underground tunnel service have advanced. This comes after Shetland councillors agreed to move forward with the proposals for the tunnels' construction, which was described as "a significant step."

A report on the future of Shetland's inter-island transport was presented to councillors for the first time on Wednesday. It recommended improved ferry services for Fetlar, Foula, Papa Stour and Skerries, together with the case for tunnels to Bressy, Unst, Whalsay and Yell.

In response to the report, councillors have now agreed to fund a study to establish the commercial and financial viability of a tunnel system, reports The National.

Council Leader Emma Macdonad said: "Tunnelling in Shetland is, ultimately, about future-proofing our island population.

"Transport connectivity is central to creating sustainable islands which provide good homes and good jobs for our people, and which reverse decades of depopulation."

Inter-connectivity tunnels such as the ones proposed can be found in the Faroe Islands, located between Iceland and Norway.

She added: "The experience of our neighbours in the Faroe Islands is clear - tunnelling from mainland Shetland to our outer islands could increase their population, lower their average age, and increase their economic prospects."

Ms Macdonald also said that they must continue to invest in a reliable ferry service as well. Referencing Wednesday's meet, she said: "This represents a significant step towards the construction of tunnels between our islands."

Isle MP Alistair Carmichael also expressed his excitement about this project, saying it was time to deliver on this long-awaited promise. The MP described the tunnels as potentially transformative for the region's economy.

Mr Carmichael added: "It has been a long road just to reach this point and there is still a long way to go but I am glad that progress is being made."

He concluded that he is excited to continue the pace, and he waits for further talks with the UK and Scottish governments.

Engineering consultancies COWI, Stantec and Mott Macdonald have been working together on the study, and uncovering how transport links between islands could be improved over the next 30 years. 

According to the National, Wednesday also saw the discontinuation of a potential Feltar tunnel for the time being.