Mr Mackison said the publicly-owned firm was "dealing with an exceptional set of circumstances".

"Challenges with several vessels in the fleet have converged at the same time, creating a significant capacity issue which leaves us with difficult choices to make in terms of service provision," he added.

"Given the age of our fleet and the need to overhaul all vessels outside of the busy summer season, our vessels are spending a record amount of time in overhaul this winter.

"This stretches our services and, when unplanned delays such as those we're experiencing with MV Isle of Lewis and MV Clansman are factored in, our resources to the limit"

The lack of vessels means a Troon-only service to Arran will continue - using the new ferry Glen Sannox and catamaran Alfred - and the more frequent services from Ardrossan will not resume until Caledonian Isles returns in April.

A shared service for Barra and South Uist has been extended.

Mr Mackison said: "The extension of the shared service is far from ideal but is the only deployment plan available to us which allows us to maintain services and meet demand across the network."

The Ardrossan-Campbeltown route has been cancelled for a third year in a row.

Full details of services are available at the CalMac website., external

Four new large Calmac ships are being constructed at a shipyard in Turkey, with the first due for delivery in the coming months, but all four are delayed and will require weeks of crew familiarisation trials before entering service.

MV Glen Sannox, built by the Ferguson shipyard, began scheduled sailings in January after years of delays, offering a significant boost for Arran services.

Its sister ship Glen Rosa is currently due for delivery in September but a further delay is expected and a new update from the yard is awaited.

A newly-constructed Australian ferry will be moved from Edinburgh to the other side of the world after leasing negotiations broke down.

Often described as a "fiasco", the Spirit of Tasmania IV has been docked in Leith for three months due to issues with existing infrastructure in the Tasmanian city of Devonport.

Operator TT-Line said it had been engaging with a broker to lease the ferry, however an agreement could not be reached.

The Tasmanian government has now ordered the ferry operator to relocate the 212m-long (695ft) vessel to the island.

The ship was built at a yard in Finland, but had to be moved to Scotland before winter over concerns it could be damaged by pack ice.

A new berth to accommodate the ship, and sister vessel Spirit of Tasmania V, may not be ready until late 2026 or 2027 and the saga has sparked a huge political row in Australia.

The vessel was due to operate in the Bass Strait, between Tasmania and the Australian state of Victoria, and had been described as a "game-changer" for the island's tourism industry.

However, it has seen a series of delays in its construction, skyrocketing costs and problems upgrading the current berths - mirroring many of Scotland's own ferry problems.

Tasmania's infrastructure minister, Michael Ferguson, and the chairman of ferry operator TT-Line, which is state-owned, resigned due to the controversy in August.

The cost of building the two LNG dual-fuel ships has risen by A$94m (£47.5m) from A$850m (£430m) when the contract was signed in 2021.

Meanwhile the cost of upgrading current infrastructure in Devonport, which handles about 450,000 passengers a year, has more than quadrupled from an original estimate of A$90m (£45.5m).

TT-Line was paying A$47,534 (£24,031) per week to berth the ship at Forth Ports, according to figures published by the Tasmanian government.

Last week Australian media reported there was a possibility of the ferry being used to house Ukrainian refugees in Scotland.

However the Scottish government quickly dismissed this saying: "This is not true and we have no plans to lease this or any other vessel for this purpose."

Tasmania's transport minister Eric Abetz said that the government had done all it could to secure a lease that would benefit Tasmanians.

He said: "We had an opportunity to secure an agreement worth tens of millions of dollars for the Tasmanian taxpayer, and it would have been economically irresponsible not to explore this.

"Previous similar leases provided more than €50m (£41.2m) to vessel owners, and it was prudent that we sought similar arrangements for Tasmanian taxpayers.

"The relentless negativity is hurting the state's economic opportunities, and it's time to move forward together."

Tasmanian Labor, the opposition party, welcomed the "backflip" from the government but said it came four months and and millions of dollars too late.

A spokesman said: "The ferry fiasco has been the biggest infrastructure stuff-up in Tasmania's history, but the cover-up has been even worse than the crime."

Delivery dates for a fleet of CalMac ferries being built by a shipyard in Turkey have been pushed back again due to problems with labour shortages.

According to a letter from the government-owned ferries procurement company CMAL, the first of the fleet will not be finished until the end of June at the earliest when it was originally expected in October.

It comes at a trying time for CalMac - the west coast operator is facing a shortage of ships and has been grappling with an "exceptional" series of problems with its fleet.

Transport Scotland said the latest delay was "disappointing" but had been caused by global issues "outwith the yard's control".

Problems with the delivery of the ferries from the Cemre yard in Turkey were confirmed in a letter from CMAL to the net zero, energy and transport committee on Friday.

The letter has not yet been published on the Scottish government website, but was shared on social media by the Islay Community Council.

It said: "We are facing serious issues with labour, particularly the availability of specialist commissioning sub-contractors.

"This continues to set the project and delivery back."

It said while the yard builds the vessels and installs machinery, manufacturers need their own specialists to commission the systems to ensure warranties are secured.

"The lack of commissioning engineers is an issue affecting the global shipbuilding industry, and is causing months-long delays in some cases," it added.

The letter said snow and cold weather had also delayed the docking of the Isle of Islay to check underwater parts and complete painting.

The first of the Turkish ferries, MV Isle of Islay, was launched a year ago by Morag McNeill, the chairwoman of CMAL, in a ceremony at the Cemre shipyard.

The second ship, MV Loch Indaal, was launched three months later by the wife of CMAL's vessel's director Jim Anderson.

A freedom of information request from BBC News revealed that a total of 10 CMAL staff and their guests attended the Loch Indaal launch ceremony, with flight and accommodation costs totalling nearly £10,000.

Isle of Islay - destined for the Islay route - was pushed from October to mid-February and will now be delivered "no earlier than the end of Q2 in 2025".

CMAL said it expected the other three vessels to "follow a delivery schedule of six-month intervals from the delivery of MV Isle of Islay".

This would mean that Loch Indaal, also for the the Islay route, would not be completed until the end of the year at the earliest, when it was due for June.

The latter smaller vessels, MV Lochmor and MV Claymore are due to be deployed on the Little Minch routes between Skye, Harris and North Uist.

The CMAL letter added: "The contract has anticipated intervals of four months, but it is prudent we take our current understanding of the situation into consideration."

A Transport Scotland spokesperson said that shipyards across the world have been impacted by external supply chain and internal resourcing challenges.

They said: "Cemre are working actively to outfit, test, trial, survey and complete the vessels as early as possible.

"We continue to make clear our strong expectation to CMAL and CalMac to closely monitor progress on delivery and deployment timescales.

"Following planned sea trials and commissioning work, a clearer indication on delivery, and that of the three sister vessels, will be provided by CMAL.

"The quality of the workmanship and construction of the vessel is fully meeting CMAL expectations and we look forward to the vessels joining the fleet and serving island communities for years to come."

CalMac recently laid out how it had re-jigged services to cope with pressure due to repair delays and new issues identified during annual maintenance.

Chief Executive Duncan Mackison said a third of its large vessels were currently out of action or operating with reduced capacity.

The charter of the privately-owned catamaran Alfred - said to cost £1m a month - has now been extended to the end of May to maintain services. The summer-only Ardrossan-Campbeltown service remains suspended for another year.

MV Caledonian Isles, which operates on the Arran route, has been out of action since last February with a series of issues including rust and twisted frames.

The ship was due back next month, but this has been pushed back, possibly to late April, after new issues were found with the tubes for its propeller shafts.

MV Isle of Lewis, which operates to Barra, needs steelwork replaced during annual maintenance, and will not return to service until Sunday 23 March, almost a month later than expected.

MV Clansman has also been slightly delayed in overhaul, while MV Isle of Mull is restricted to just 45 passengers.

This is due to problems with its emergency evacuation systems, which will not be fixed until mid-May at the earliest.

The new Ferguson-built ferry Glen Sannox joined the fleet earlier this year and its sister ship Glen Rosa is due for delivery in autumn.

Glen Sannox is serving the Arran route but is currently too big to berth at the Ardrossan harbour, sailing instead from Troon.

Scottish Conservative transport spokeswoman Sue Webber said: "This is yet another blow to Scotland's betrayed island communities, who are sick to the back teeth of delays to upgrading their decrepit ferry fleet.

"The buck stops with SNP ministers who are responsible for this national scandal. Islanders must wince every time they hear of an update from CMAL or CalMac because it's always more bad news.

"This latest delay couldn't be worse timed, with the summer schedule already scaled back because so many ageing ferries require repairs.

"It defies belief that no SNP minister has resigned or been fired for inflicting this chaos on the country."