Train drivers could strike for the first time in 20 years after talks between a rail union and transport bosses failed to reach an agreement over pay.
Aslef met with ScotRail on Monday to discuss a pay increase amid rising inflation and the cost-of-living crisis.
While other sections of ScotRail staff have gone on strike in recent years, the move would be a first in two decades for drivers.
It is understood ScotRail has offered drivers a 2.2% increase, which Aslef says is a "derisory offer".
Kevin Lindsay, industrial organiser for Aslef, said: "Aslef members who have kept the country moving throughout the pandemic have been presented with a derisory pay offer from ScotRail management which takes no account of the cost-of-living crisis workers face.
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"Scotland's train drivers did not make the decision to consider industrial action lightly - indeed we have not had a single pay dispute with Scotland 's railway operators for 21 years. Yet, just one month into the Scottish Government's stewardship of ScotRail, we are being left with no option but to consider action in response.
"ScotRail and the Scottish Government must recognise that these key workers deserve a decent pay rise, they should return to the negotiating table with a much fairer deal that recognises the vital work our members do."
Neil Bibby MSP, Scottish Labour transport spokesman, said: "This is a shameful way to treat hardworking rail staff, who kept things going through the pandemic.
"If public ownership is going to mean more than a coat of paint and a photo op, the SNP need to treat workers with respect and give them a fair pay deal."
Graham Simpson, transport spokesman for the Scottish Conservatives, said: "The SNP promised a bold new era when they nationalised ScotRail - but within a month they look set to transport passengers back to the 1970s.
"The public have already been saddled with combination of rising fares and a reduced service, now they are threatened with even more disruption due to strike action.
"This is quite unacceptable at a time when demand is increasing as more and more people return to normal work patterns post-pandemic.
"Ministers and ScotRail must return to the negotiating table to thrash out a deal that averts strikes or risk their much-touted nationalisation descending into chaos."
A Transport Scotland spokesman said that "rail unions have long campaigned for public ownership" and the Scottish Government "has delivered our railways back into the public sector control".
"The transport minister has frequently met with rail unions in recent months and we absolutely understand the unions' desire to negotiate a fair settlement for their members," the spokesman said, adding that Transport Minister Jenny Gilruth had recently "provided clear support for the RMT in their current pay dispute with Network Rail at a UK level".
"Rail unions are aware any increase in excess of public sector pay increases have a clear process which must be followed which includes cabinet approval.
"We would encourage them to continue meaningful dialogue with ScotRail so a mutually agreeable outcome can be reached as soon as possible.
"It is our intention for ScotRail and its staff to benefit from the transition to public sector control and that is why we would call on everyone involved to take time to consider all options carefully."
