Almost one third of ScotRail services are to be axed just over a month after the rail operator was taken into public ownership.
A temporary timetable will be introduced from Monday, bosses announced on social media.
The changes will see around 600 daily services cut across Scotland due to a shortage of drivers in an ongoing pay dispute.
A ScotRail spokesperson wrote on Twitter: “From Monday, May 23 we’ll be bringing in a temporary timetable to make sure the service we provide customers is as reliable as possible.
“Please check your journey on our as train times on your route may have changed.”
Transport minister Jenny Gilruth was challenged on the announcement in the Scottish Parliament on Wednesday afternoon.
She was asked about discussions held between the Scottish Government and ScotRail regarding services returning to pre-pandemic levels.
She told the chamber the rail operator will keep its timetable under review.
But Russell Findlay, who lodged the question, pointed out that the transport minister had not made reference to the newly-announced revised timetable.
The Conservative MSP said: “Nearly one third of their services will be cut.
“That’s 600 daily services across Scotland.
“At this rate they will have more ferries than trains.
“This will cause absolute misery for passengers up and down the country.
He asked Ms Gilruth who she feels is responsible for a “calamitous chapter” for rail in Scotland.
The transport minister said she does not agree with the characterisation of the Scottish Government’s handling of public ownership of ScotRail.
Ms Gilruth said Wednesday’s announcement by ScotRail was down to the fact that some drivers “did not take up the option of overtime and rest day working” following the decision from drivers’ union Aslef to ballot for industrial action over pay.
She told MSPs the revised timetable would give a “more stable and reliable service” to passengers.
Ms Gilruth also called on trade unions who campaigned for public ownership to “come back to the table” to negotiate an agreement.
Tory transport spokesman Graham Simpson said the move was “damning, but not surprising”.
He added: “Not only are existing passengers being let down by these enormous cuts, but the SNP-Green Government – obsessed with taxing cars off the road – will have no hope of increasing public transport use while it slashes services.
“With all the disruption of the past few years, it is quite an achievement that the SNP has managed to sink ScotRail to a new low.
“Jenny Gilruth must urgently look to reverse these cuts or lose what little credibility her Government has left.”
David Simpson, ScotRail service delivery director, said: “We are very sorry to customers for the disruption of recent days. We know what customers want more than anything is certainty and reliability, which is why we are introducing a temporary timetable.
“We want to resolve this dispute with the trade unions and move forward together to provide the safest, greenest, and most reliable railway we can for Scotland.
“We remain open to further talks with the trade unions.”