TWO long-awaited lifeline ferries to serve Scotland's island communities have been delayed indefinitely and it could add  millions of pounds to the cost of the £97m project, a senior minister has revealed.

One of the ferries, MV Glenn Sannox - which is destined for the Arran-Ardrossan route was due to enter service last summer but construction delays meant that was initially put back to this summer.

The second vessel, known as Hull 802, was supposed to be delivered to CalMac in the autumn of last year for use on the Uig-Lochmaddy-Tarbert triangle, and had then been due to be delivered in the Spring of next year.

It comes as it emerged as ferry builders Ferguson Marine Engineering Ltd (FMEL) and project overseers Caledonian Maritime Assets Ltd (CMAL) are involved in a contractual dispute over costs.

The new ‘dual fuel’ boats, which can use both diesel and liquified natural gas, are being built by Ferguson Marine Engineering Ltd, owned by Monaco-based billionaire Jim McColl, a member of the First Minister’s council of economic advisers.

And the Scottish Government has confirmed there has been a delay on even these delays.

READ MORE: Revealed: CalMac's 'disastrous' decade of ferry cancellations and delays

Islands minister Paul Wheelhouse has written to Ferguson Marine seeking a new programme and cost to complete both vessels.

He said of the rescheduled delivery of MV Glen Sannox and Hull 802: “It is clear that they will not be achieved.”

HeraldScotland:

News of the latest delays comes amid continued calls for increased capacity on the Clyde and Hebrides ferry network to meet greater demand from islanders and tourists.

Scottish Conservatives raised concerns that as it stands, 16 of the 52 CalMac vessels are beyond their 25-year life expectancy.

Scottish Conservative transport spokesman Jamie Greene said of the delays: “This is a significant admission from the SNP government that, having been already delayed by 13 months, these vessels are going to be pushed back even further.

“Not only has the delivery of both vessels been pushed back for a second time, but we’re now learning that the cost is likely to be revised.

“That means the Scottish taxpayer will have to stump up the extra cash for this astonishingly poor project planning.

“The public is already paying out £20 million every year just to maintain the existing ferry network and is facing the prospect of being landed a bill to the tune of tens of millions of pounds.

READ MORE: Ferguson Marine shipyard predicts £44m loss on CalMac ferries

“This is rapidly turning into a national scandal and has raised some serious question of the SNP’s ability to manage Scotland’s ferry network.”

Mr Wheelhouse, in a letter said to Edward Mountain, convener of the rural economy and connectivity committee: "We have taken all possible steps to understand the options available to ministers so that we can continue to support the workforce building these vessels."

HeraldScotland:

He confirmed that a contract price increase claim was submitted by Ferguson Marine in December 2018. But CMAL refuted the basis of the claim.

"While the Scottish Government is not a party to the contract between the companies, this ongoing delay is extremely disappointing when the Scottish Government have already provided loans to FMEL totalling some £45 million to develop the shipyard and support completion of these vessels," said Mr Whitehouse.

In August, the shipbuilder blamed technical challenges in constructing the dual-fuel ship, which can be powered by liquefied natural gas for delays.

In March, the Scottish Government and its vessels and harbour offshoot CMAL were asked to speed up the completion of MV Glen Sannox and Hull 802. Bosses from CMAL had accused Ferguson Marine of not doing enough to get the ferries finished - something the company has strongly denied.

The ferries were ordered in 2015 to ease the strain on the stretched and ageing fleet of Gourock-based operator CalMac.

HeraldScotland:

A general view of the CalMac ferry Glen Sannox under construction at the Ferguson Marine shipyard on September 14, 2018 in Port Glasgow, Scotland. (Photo by Jamie Simpson/Herald & Times)

Ferguson said in March that they expect to lose almost £40m on the deal and want more money to finish the vessels because they have incurred 'significantly higher costs', something which they claim is because of major changes to the vessels.

But CMAL had argued that only 'minor' alterations have been made and say they have already paid nearly £1.5m for those from a £3m contingency fund - on top of the entire £97m budget for the contract.

A CMAL spokesman said of the latest development: "We have urgently requested an updated timeline for completion of both ferries, and we are awaiting a response from FMEL. This has not been forthcoming at this stage.

"However, we concur with the assessment that the delivery date for MV Glen Sannox cannot be achieved. We, along with CalMac, Scottish Government and Scottish taxpayers, in particular those in island communities, eagerly await the arrival of the new vessels and we urge FMEL to focus on their completion.”

FMEL declined to comment at this stage.