Islanders are facing a “challenging and difficult” winter because of potential disruption to ferry services, Scotland’s transport minister has warned.

Fiona Hyslop said Caledonian MacBrayne was under intense pressure because of a lack of available vessels – but that she was pushing the ferry operator to consider “all options” to maintain lifeline services.

She was responding to an urgent question from one of her own backbenchers after it emerged the main Arran ferry MV Caledonian Isles may be out of action all winter.

Scottish Conservative MSP Jamie Greene accused of the SNP of having a “brass neck” for blaming CalMac for problems it had created through years of underinvestment.

Hyslop told MSPs the latest delay to the return of Caledonian Isles – which has been out of action since January – was “deeply frustrating and concerning”.

“Ministers and officials continue to push CalMac to ensure all options to expedite repairs are being considered,” she said.

She said CalMac was now looking at what it meant in terms of vessel redeployment across the entire west coast ferry network.

She said three options had been shared with island communities before route changes are announced next week.

But CalMac had to balance the importance of the busy Arran route with the need to maintain lifeline services elsewhere, she added.

“That’s the difficult balancing act in what is going to be a challenging and difficult winter,” she said.

“We thought that last winter would be the period that would have caused most issue, and we should have seen at least the Glen Sannox vessel in by now.”

Scottish Conservative MSP Jamie Greene accused the SNP of having a “brass neck”, saying the the government was ultimately to blame for the problems, rather than CalMac.

“Let me tell you where the failures lie in this entire ferry scandal – it’s right there on the SNP front benches,” he said.

“That is the reason – the lack of investment, the lack of progress in new vessels. I haven’t heard a single solution from the minister today on what CalMac is going to do to address this situation.

“The are completely out of vessels and they are completely out of options.”

Hyslop said that was untrue, and that CalMac still had options to maintain services.

The west coast ferry operator is facing a perfect storm of problems as it tries to plan a winter schedule without two of the 10 major vessels it normally relies on.

MV Caledonian Isles has been out of action since serious corrosion was discovered during annual maintenance in January, which required the removal of all its engines while repair work was carried out

The 31-year-old ship returned from the Cammell Laird shipyard in Merseyside last month, but before it could carry passengers again, a new gearbox fault was detected which required several more weeks to fix.

On Tuesday, CalMac revealed more problems had been discovered which could put the ship out of action until late March.

Another large ferry, Hebridean Isles, will be retired later this month because it is no longer considered feasible to get it through its mandatory five-year survey

The long-delayed Arran ferry Glen Sannox, being built at the Ferguson shipyard, is three weeks past its latest delivery date.

Once delivered, CalMac will need six-and-a-half weeks of crew familiarisation trials plus an already-booked annual overhaul in December before it becomes operational.

Several other vessels will have to be withdrawn from service for their scheduled winter maintenance work in the coming months.

The arrival of the first of four new large ferries being built in Turkey has also been delayed until March next year.

A plan to charter an extra large vessel, MV Ben-My-Chree, from the Isle of Man Steam Package Company was dashed last week when the ship was unable to berth safely at Brodick harbour on Arran.

CalMac is currently maintaining ferry services to Arran using the Ferguson-built MV Isle of Arran – nicknamed the “Auld Trooper” because it is 40 years old – and a catamaran MV Alfred which is being chartered at a cost of £1m per month.

Government-owned CaMac used to add a new large vessel to its fleet every two or three years, but since 2007 the role of ferries procurement has been the responsibility of a different state-owned company, CMAL.

Since then only two large vessels have been delivered, MV Finlaggan in 2011 and MV Loch Seaforth in 2015.

The dual-fual LNG ship Glen Sannox and its sister vessel Glen Rosa were both meant to be delivered in 2018.

But design challenges and a bitter dispute between CMAL and the former Ferguson shipyard owners over costs resulted in the firm going bust and being nationalised.

Much of the CalMac fleet is now beyond its expected service life.

Fiona Hyslop pointed out that six new large vessels are under construction – including Glen Sannox and Glen Rosa which are both earmarked for the Arran route.

CMAL has also begun the procurement process to replace seven small ferries, with the contract expected to be awarded next March.