AN urgent line needs drawn under the controversial proposals to relocate one of Scotland’s historic ferry routes for the sake of passengers and taxpayers, the country’s biggest transport union has said.

Wading into the bitter saga over which port the Arran service will operate from, the RMT said ministers needed to “end the uncertainty” and retain the link between the island and Ardrossan and Ayrshire.

Claiming it was confident the Scottish Government would give the go-ahead for Ardrossan, it called on ministers to guard against “opportunist proposals from private operators, attracted by talk of public investment” as well as the “introduction of low cost crewing practices on Clyde and Hebrides routes”.

But the firm bidding to lure the service 15 miles south to affluent Troon insisted its plans avoided the need for any public cash and reiterated its stance its proposals would be more reliable.

Ardrossan is campaigning to retain the 180-year-old service amid attempts by Associated British Ports (ABP) to shift it to Troon, around 15 miles further south.

APB recently lost a service to Northern Ireland from the affluent South Ayrshire town and has promised to invest £8m if the Arran service is transferred to the mothballed Troon port.

The battle has sparked claim and counter claim, with Ardrossan claim its bid could be delivered a year ahead of its rivals and a saving to the taxpayer of £160m-plus over 30 years.

ABP’s key pitch has been that Troon is more resistant to poor weather conditions.

Just weeks after it was announced that all of Scotland’s £1billion-plus ferry services would be nationalised with costly and time-consuming tendering exercises binned under new plans pursued by ministers, RMT said the Government’s decision would be “critical to the development of CalMac services and vessels on this part of the publicly-owned and operated ferry network”.

RMT general secretary Mick Cash said: “Making Ardrossan a modern, multi-modal harbour capable of serving the social and economic needs of island and mainland communities should be a major priority for the Scottish Government.

“In our view the Scottish Government needs to end any uncertainty and get on with developing Ardrossan to the benefit of passengers, staff and businesses.”

Steve Todd, RMT national secretary, added: “The Scottish Taxpayer is spending £48.5m on a state-of-the-art ferry from 2018 for the Ardrossan to Brodick route. That needs Ardrossan to be ready for the new vessel.

“We are confident that the Scottish Government will give the green light for that work soon. Opportunist proposals from private operators, attracted by talk of public investment are unhelpful and risk the introduction of low cost crewing practices on Clyde and Hebrides routes. That is something RMT members and their union will never accept.”

An ABP spokesman said: “ABP’s bid is unique in that it requires not one penny of public funds. Unlike the proposal from Ardrossan, ABP is offering to invest £8m to build brand new facilities, which, together with Troon’s unsurpassed reputation for reliability, offer a transformation in the quality of service for the people of Arran and a better deal for the Scottish Government.”

During the recent tendering process for the Clyde and Hebrides routes, trade union leaders accused ministers of preparing to privatise CalMac’s heavily subsidised services.

Transport Scotland said a decision would be made in spring.