Mr Mackay made the announcement as part of his visit to the site in Shetland where he met staff and was given a tour of the facilities, including the recently refurbished helicopter arrivals area.

The second phase of work will see the terminal undergo a programme of repairs and refurbishment, cladding replaced on the fire station and air traffic control building, and work carried out to upgrade the airport’s apron.

Mr Mackay said: “I’m delighted to announce funding for the next phase of work at Sumburgh Airport, which will allow the site to go from strength to strength.

“The airport plays a hugely important role for the oil and gas industry and has seen passenger numbers and aircraft movements double over the past four years.

“The first phase of the work focused on upgrading the hangers and has proved a real success, with Bristow Helicopters moving operations onto the site and another tenant due to be announced shortly.

“The second phase will see a programme of repairs carried out to the terminal building, which dates back to the seventies, and a revamp of its interior with new check in, security and passenger facilities.

“Repair work will also be carried out on the fire station and the air traffic control building, as well as the airport’s apron, and a purpose built storage facility for airport vehicles will also be constructed.

“We want Sumburgh Airport to continue this success and the next phase of development will allow them to build on the work that has gone before.

Inglis Lyon, managing director of Sumburgh Airport operator Highlands and Islands Airports Limited said: “This is a tremendous vote of confidence by the Scottish Government in the future of Sumburgh Airport. Sumburgh has enjoyed unprecedented growth in recent years and, with further growth forecast, it is right that we invest for the future to ensure that Sumburgh continues to deliver a good experience for all passengers.

“We have already delivered significant improvements to the airport including enhanced facilities for the oil and gas sector that will help ensure Sumburgh is better equipped to accommodate continued growth in the energy sector.

“The next phase of investment will deliver a better experience for scheduled passengers and allow us to upgrade essential airfield services.

“Sumburgh Airport is an essential link in Shetland’s transport infrastructure and performs a vital economic role as an energy hub for Scotland. This substantial investment by the Scottish Government will ensure the airport is better equipped for the future.”