Hundreds of train journeys are believed to have been cancelled on Sunday as Scotrail continues to deal with a shortage of drivers and the threat of strike action.
More than 300 services were listed as 'cancelled' by the operator's official journey tracking website early on May 29.
Only some of the journeys are being replaced with bus services. Elsewhere, Scotrail has overhauled its refund policy to allow those unable to travel to receive a full refund.
The railway giant previously said it had been unable to agree a temporary timetable of guaranteed journeys for Sundays after doing the same for weekdays and Saturdays.
Instead, the train operator is effectively cancelling journeys on the fly as it ascertains whether it has enough crew at any given point during the day.
It told travellers in a tweet posted early on Sunday: "Changing timetables is complex. We’ve brought in temporary timetables Mon–Sat, but we’re still working on Sundays.
"Today it's the normal timetable so there'll be cancellations. We're sorry for this disruption."
A lack of staff has forced Scotland's railway operator to slash a third of all services until the row is resolved.
Drivers have refused to work overtime or on rest days amid an ongoing pay dispute between Scotrail and train driver unions Aslef and the RMT.
Shop stewards refused an early 2.2 per cent pay rise deal offered by Scotrail bosses but will put an improved 4.2 per cent offer to workers in the coming days.
Failure to reach a deal could see drivers walk out.
Rail bosses have implemented a temporary timetable of guaranteed journeys running Monday to Saturday, adding later journeys on Friday and Saturday nights following criticism.
However, some services are terminating as early as 6pm on other days.
David Simpson, Scotrail's service delivery director, said: "Unfortunately, it has not been possible to publish a temporary timetable for this Sunday.
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"That means the normal timetable will be in operation, however, there will be cancellations as a result.
“The complexities of pulling together such widespread changes to timetables means that it's not possible to do so in such a short space of time.
“We apologise to customers and advise them to check their journeys before travel.”
Scotrail was taken into public ownership in April as a "last resort" measure after Dutch operator Abellio's management was deemed poor value for money.
Transport Minister Jenny Gilruth, with whom responsibility for Scotrail rests, said last week that the Scottish Government was "absolutely committed" to reaching an agreement with the unions.
She told MSPs: "I want nothing more than for us to restore the previous timetable that was in place. Passengers need certainty."
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