Rail bosses have said they are “deeply disappointed” after staff on the Caledonian Sleeper service announced they would take strike action.
Workers on the Aberdeen to London route accused the firm that runs the service of going back on its promises.
Trade Union RMT said Serco had gone back on pledges to address staffing concerns.
RMT said workers on the overnight route will now not be booking shifts between noon on September 29 and noon on October 1.
Union members will also be asked not to work any overtime and not to perform higher grade duties from October 2 until further notice.
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Ryan Flaherty, Serco’s managing director of the Caledonian Sleeper, said: “We are deeply disappointed and frustrated at this industrial action by the RMT, but most of all we are bemused as they have been unable to explain what will bring this dispute to a resolution.
“We have met the RMT on many occasions and the changes they have requested have either been completed or are under way, including the recruitment of more staff.
“We recognise that the problems we had introducing the Lowland Sleeper were challenging for everyone involved and we are very grateful to all our staff for their efforts and the way they rose to meet the challenge, but we are pleased that in the past weeks the situation has been steadily improving.
“This action is completely unnecessary and we urge the RMT to come back and tell us what they want. We are ready to go to mediation and hold further discussions.”
RMT bosses claim that “insufficient progress” has been made in talks with Serco.
General secretary Mick Cash said: “The union is angry and frustrated that promises made to us to address the serious concerns of the Caledonian Sleeper staff at the end of July have not been honoured.
“RMT members have been put under intolerable personal stress as a result of the company’s mismanagement of the sleeper service.”