SCOTLAND'S lifeline ferry network faces at least another two weeks of disruption after plans to have its largest vessel back in service were put off for a fifth time in a month.

MV Loch Seaforth was taken off the Ullapool-Stornoway route by state ferry operator CalMac a month ago to be taken into dry dock for "major" engine repairs.

The publicly funded firm had initially said the eight-year-old vessel would out of action until "at least the end of April" at the earliest but has since kept putting that date back. On Thursday CalMac said it was expected back by May 21 at the earliest.

Now as the islands start to open up to visitors with the easing of Covid-19 restrictions, the return of the vessel has been pushed back yet again to May 28 at the earliest.

CalMac said that "ongoing repairs" on Loch Seaforth have revealed "further issues" which will require attention before the vessel can return to service.

READ MORE: CalMac ferry network crisis as breakdowns cause three day island freight shutdown

It comes a matter of days after Scotland's crisis hit lifeline ferry network came under fresh fire after a new series of breakdowns and setbacks with five of its fleet leading to service cancellations and restrictions as new pressure is put on ministers to take urgent action.

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The Herald revealed how the failure of Loch Seaforth resulted in cuts to other services across the ferry network as vessels relied on with other routes were shifted around to accommodate.

Campaigners had described the situation as a "national scandal" and that those responsible should already have lost their jobs for the state of Scotland's ferries.

It means that the temporary shifting of ferries to cover for Loch Seaforth's loss will remain in place. That means MV Isle of Lewis, which was taken off its usual route between Castlebay on the Isle of Barra and Oban in Argyle to support the Loch Seaforth run will remain.

One of Scotland's busiest ferry services, the Ardrossan to Arran route, will continue to remain serviced by one vessel, rather than two.

According to the Arran Recovery Group, the shifting of the ferry for the start of the summer tourist season will cost the island more than £500,000 in lost business.

The 38-year-old MV Isle of Arran - which normally runs on the Ardrossan to Arran route - and was taken off freight service duties on the Ullapool-Stornoway crossing because of stabiliser problems, resulting in a shutdown on services for over three days last week, will remain operating on the "more sheltered" Islay run.

There was criticism when it emerged that as Isle of Arran only had space for four lorries.

The 36-year-old MV Hebridean Isles, ended up replacing the Isle of Arran on the Stornoway crossing on Saturday causing cancellations on its usual Kennacraig to Islay.

It also means the Ardrossan to Campbeltown service which has been out of action since Loch Seaforth's major engine problems, will remain so.

A further update is expected on Monday following assessment by independent engineers who will be investigating the issue further over the weekend.

Specialist engineers working on the Loch Seaforth have reported that more work must be carried out to her engines, while the crankshaft also requires work.

CalMac said that plans are being put in place to ensure that essential freight continues to be brought to and from the Western Isles as a matter of urgency.

Temporary changes to vessels across the network will remain in place for the time being.

CalMac managing director Robbie Drummond said: “This is frustrating news, as we were expecting to see the Loch Seaforth return to service sooner than this. We will continue to work closely with customers to keep them updated of the latest situation and to minimise further disruption.”

The latest issues come off the back of the country's ferry building fiasco - and comes as the islands prepare to open up next week as Covid restrictions ease.

The two lifeline ferries being build at Ferguson Marine which were due to be in service in early 2018 are now up to nearly five years behind schedule and their cost is now over double the original £97m contract.