Proposals to centralise air traffic control for seven airports could put jobs and safety at risk, a union has warned.

Highlands and Islands Airports Limited (HIAL) has proposed creating a remote tower centre - which it said would be a UK first - as part of plans to "future-proof" its operations with an estimated £28 million investment over the next ten to 15 years.

Air traffic controllers would be moved to a central hub, the location of which has not yet been decided.

The airports involved are Sumburgh, Dundee, Inverness, Wick John O'Groats, Kirkwall, Stornoway and Benbecula.

HIAL said its airports at Barra, Tiree, Islay and Campbeltown have different levels of air traffic usage and would not be affected by the changes.

The HIAL board has agreed in principle to the move, recommended in a report by aviation consultancy Helios, and will now hold further talks with staff, stakeholder groups and politicians about the implementation of the project.

Air traffic controllers union Prospect has raised concerns about the proposals.

David Avery, Prospect aviation officer in Scotland, said: "Prospect supports HIAL's need to modernise its infrastructure to keep up pace with regulations and that this will require significant investment.

"However, any centralised monitoring system will be dependent on a reliable, resilient and secure communications infrastructure between the mainland and the island which simply does not exist.

"HIAL are gambling on this and Prospect believes this is gambling with people's safety.

"Air traffic control provides high-quality, skilled, highly-paid employment in the islands with many controllers recruited and trained locally. Centralisation will remove these roles from the islands.

"We do not believe the report has given sufficient weight to these considerations and HIAL's role as an employer in the Highlands and Islands."

HIAL, which is owned by the Scottish Government, said there will be no immediate changes to its operations, with the plans proposed over ten to 15 years.

It said the long-term remote towers and centralised approach surveillance control programme will mirror an already successful project in Sweden.

HIAL managing director Inglis Lyon said: "Our overriding priority is and will always be to deliver safe and secure air navigation services that will keep our airports open for local communities for the long term.

"Given the nature and location of our business and airports, we are already managing a number of challenges.

"These include staff recruitment and retention, increasing regulation and increasing pressure on costs.

"Our role is to ensure that the airport network benefits from investment in its long-term future, secured through new technology."