CALMAC has been forced to bring in a relief vessel for the second time in less than two weeks on the same route after another breakdown of one of its ageing ferry fleet.

At the end of June, a steering fault with 26-year-old MV Loch Alainn meant that the services on the inter-island ferry between Barra and Eriskay - used as an alternative route to the beleaguered South Uist route - had been cancelled for three days.

The Scottish Government-owned ferry operator has now had to charter another vessel to provide a passenger-only shuttle service after a fresh technical issue which required further investigation was discovered at around 5.30pm on Sunday.

It has now been withdrawn from service and users have been warned that no vehicles were being carried on Monday.

The issue is with the vessel's 'void space' an enclosed section in the cargo area and CalMac said a repair plan is being drawn up.

READ MORE: 'CalMac are not interested in helping the islands':  Fury as Scots ferry cuts remain

CalMac said the vessel was removed from service due to "water ingress".

MV Loch Bhrusda is being deployed to the Sound of Barra and is expected to arrive on Tuesday afternoon at the earliest.

MV Lord of the Isles is operating a service between Barra and South Uist on Tuesday  accommodate cancelled traffic.

The service was last month providing an alternative route to Lochboisdale on South Uist - which had all services stopped for most of last month due to other breakdowns and delayed annual maintenance checks and has been at the centre of major island protests.

The 38-year-old MV Hebridean Isles, which has been hit with issues since Boxing Day, was out of action and remains so.

It was removed from the CalMac firing line on February 16 with freight services providing vital supplies to Arran from Troon suspended.

The vessel was forced back into dry dock as the vessel experienced what the Scottish Government-owned ferry operator CalMac described as "pitch control issues".

CalMac cancelled sailings to South Uist for most of June after MV Lord of the Isles, which runs between Mallaig and Lochboisdale, was redeployed to Islay as the ferry operator looked to juggle its vessels across Clyde and Hebrides services.

The ferry operator then had to charter the passenger-only boat Karleen Belle from Uist Sea Tours to run services between Barra and Eriskay. MV Alainn is big enough to take 150 passengers and 20 cars.

The Herald: Robbie Drummond of CalMac

The ferry operator brought back MV Lord of the Isles early to provide a one off relief sailing for cars so that people hit by the MV Loch Alainn failure were able to get off Barra. The service was to take people between Castlebay and Lochboisdale which has been out of action since the start of the month.

The issues arose after a public meeting on South Uist attended by 250 people and CalMac chief executive Robbie Drummond which registered a vote of no confidence in the ferry operator.

The move to visit South Uist came after an estimated 500 residents, 200 cars, 40 vans and 20 lorries converged on Lochboisdale - the port which links South Uist to the mainland - to protest about the decision to stop nearly all services over June.

One ferry user group official said: "It is the way of things at the moment, that just when you think a ferry is back up and running, it is out of action again. It just again shows how much extra capacity and resilience is so desperately needed."

It comes as the more modern 11-year diesel-electric hybrid MV Hallaig, which was the first ship to be fully built on the Clyde in over five years when it launched in 2012, was put out of action for a short time due to a sewage system problem on Monday with sailings cancelled on the route from Sconser on Skye and the island of Raasay.