Proposals to move Arran’s lifeline ferry link from the north of Ayrshire to its south have been branded as “nothing short of cataclysmic”.

The firm which owns the port in well-to-do Troon has offered to invest £8m in the town if it can poach lucrative links to the Clyde island from poverty-hit Ardrossan.

Associated British Ports has pledged to redevelop the mothballed ferry dock in Troon, South Ayrshire, which recently lost a service to Northern Ireland.

But it will only do so if it can lure the government-owned and subsidised Calmac ferry service from is current mainland port at Ardrossan, North Ayrshire.

ABP’s pitch has infuriated political leaders in North Ayrshire for whom the ferry, which goes to Brodick on Arran, remains a vital job-creator and tourist draw. North Ayrshire’s newly elected council leader, Joe Cullinane, said: “Our studies show that the ferry terminal supports 165 jobs in the area - equivalent to £4.4 million per annum in wages - and that’s not counting other income to the area in the form of tourism and resident shopping patterns.

“The loss of the ferry port would be nothing short of cataclysmic for our area.

“We do, however, remain positive that common sense will prevail and that the Arran ferry will continue to run from Ardrossan for many, many more years to come.”

North Ayrshire has argued that its route from Ardrossan is quicker but ABP counter that their service would be more reliable. One of the firm’s directors, Andrew Harston, said: “For the community on Arran the connection to the mainland is absolutely vital and this should not be left to the mercy of the weather, as it has been for too long. P&O Irish Sea ferries previously relocated from Ardrossan to Troon due to the challenges of entering Ardrossan harbour in poor weather and the cancelled sailings that were the result.

“The solution being offered by ABP at Troon, which is one of the most sheltered harbours on the west coast of Scotland, would represent nothing short of a transformation in the quality of the service on offer to the islanders and tourists. Not only do we offer reliability whatever the weather, we are also proposing to build a modern passenger terminal to fully compliment the new pier and terminal development underway at Brodick.”

Supporters of Ardrossan stress that there has been recent work - with the Scottish Government - to look at ways of making the crossing more reliable. A new 100m ferry will start plying the route the year after next. Government quango Transport Scotland has expressed support for Ardrossan, said Mr Cullinane. The agency itself, however, insisted it was looking at all options. Ardrossan terminal, which is owned by Peel Ports, may need public cash to be upgraded for the new bigger ship.

The North Ayrshire port remains the focus of regeneration in an area that ranks as the 17th most deprived in Scotland out of more than 7000.

The ABP proposal effectively sets North and South Ayrshire against each other with both sides claiming better road and rail links. Ardrossan is closer to Brodick, which should mean lower fares. South Ayrshire Council is understood tobacking ABP. P&O dropped its crossing from Troon to Larne earlier this year.