Ferry services on one of Scotland's busiest routes face a new wave of disruption after divers discovered safety issues with Ardrossan harbour.

The Irish Berth was put out of action on Thursday when the harbour authority ordered all users to cease operations. It is expected to be out of action until at least January 24.

The last sailing from the berth to and from Arran was due to be 4.25pm on Thursday.

The berth is the only one which can be used by the emergency ferry MV Alfred, which has been chartered at a cost of £1m a month to cover for ferry operator CalMac's ageing fleet.

Another berth is still operating and a second ferry MV Isle of Arran will continue to sail to Arran.

READ MORE: MSPs' new concern over lack of oversight over Scotland's ferry fiasco

It is the latest issue to hit Ardrossan, with CalMac already making arrangements to sail to Troon when the new much delayed and over-budget ferry MV Glen Sannox finally operates.

The Herald: The Glen Sannox

That is because Ardrossan will not be ready to handle the ferry when it is finally operating - as it will have a lack of storage facilities for LNG, which the vessel uses.

CalMac stated: "Following a dive inspection at the Irish Berth in Ardrossan Harbour, the local Harbour Authority have advised that all harbour users are required to cease operations using the Irish Berth."

It said that on Friday, MV Alfred sailings from Ardrossan at 8am, 11am and 4.25pm have been cancelled, along with the sailings departing Brodick at 9.30am, 12.30pm and 5.55pm.

CalMac also warned the following other sailings operated by MV Isle of Arran are liable to disruption or cancellation at short notice due to adverse weather associated with berthing and unberthing in Ardrossan.

Finlay MacRae, head of operations for CalMac, said the operator had been advised by the port's owner, Peel Ports, that the berth would have to shut for "critical inspections".

He said: "Unfortunately, this means that we have had to withdraw MV Alfred from service as the vessel is only suitable for the Irish Berth.

"Any affected customers are being contacted and moved to MV Isle of Arran when space allows. MV Isle of Arran will continue to operate the core Arran service from the main berth in Ardrossan to Brodick."

Peel Ports apologised for the inconvenience but said safety had to be its priority.

Scottish Conservative West Scotland MSP Jamie Greene said of the latest issue: “This is grim news for Arran and Ardrossan. This development will surprise no one who has been keeping tabs on the shocking way the SNP-Green Government has treated Ardrossan and Arran.

“We now have a vessel, costing millions of pounds to lease, drafted in to replace the new Arran ferry which has cost hundreds of millions of pounds to build and hasn’t arrived yet, which itself isn’t able to dock at the port for which it was built for. You couldn’t make this up if you tried.

“To learn the temporary vessel now is unable to berth in a port which has suffered decades of underinvestment, and the SNP holding back overdue upgrades is the latest hammer blow for those on both sides of the Ardrossan to Arran ferry route.

“We need urgent clarity from CalMac on where the MV Alfred is going to port, and guarantees from SNP ministers as to what they will do to make Ardrossan Harbour fit for purpose.”

The Herald: MV Alfred

Scottish Government-controlled Caledonian Maritime Assets Limited (CMAL), which owns the nation's ageing ferry fleet signed off on the contract for two standalone liquefied natural gas (LNG) stations for two long-delayed and over-budget lifeline ferries in early April 2020.

The project handed to Danish supplier Kosan Crisplant involved designing and installing Scotland's first LNG bunkering facilities at Uig on the Isle of Skye and at the North Ayrshire coastal town of Ardrossan.

They were due to be completed in July 2022, to enable the vessels Glen Sannox and sister ship MV Glen Rosa to be fuelled with LNG which Kosan Crisplant said at the time was cleaner than any other fossil fuel.

But the work has still not started on the project and in August CMAL was unable to say when they would be completed.

The completion date given by the Danish supplier for the tanks in the summer was the "beginning of 2025" - well after the latest dates for the delivery to Scottish Government-controlled ferry operator CalMac of the much-delayed and over-budget vessels Glen Sannox and the so-far unnamed Hull 802.

Because of the storage tank issues at Ardrossan, the LNG will have to be pumped from trucks to the ship in Troon.

CalMac admit in its customer messaging that truck-to-ship bunkering is "not considered a sustainable solution" which will meet the long-term demands of the new ships.

They say the typical transfer rate is too slow – typically between two and two-and-a-half hours for 20 tonnes. When the delayed fixed tank is in operation, the time will drop to between 45 and 60 minutes.