Scottish taxpayers could be hit with a six-figure bill to cover the cost of a strike on the Caledonian Sleeper rail service.
Members of the Rail, Maritime and Transport (RMT) union staged a 48-hour stoppage to highlight their concerns about various safety issues and brought the service to a halt.
Pickets made their point at stations in Inverness, Fort William, Aberdeen and London Euston.
The sleeper franchise was taken over by Serco from FirstGroup earlier this year.
Under the terms of its contract, the company can submit a claim to the Scottish Government for losses incurred during industrial action.
If it is deemed everything possible was done to avert industrial action, then compensation will be paid.
In the case of the December walkout, it could cost about £100,000.
A spokesman for Serco said: “We haven’t made any decision about what we’re going to do. Our focus has been trying to resolve the dispute and looking after the guests affected.
“There are just over 1,000 passengers affected and the average fare is about £100.”
A spokesman for Transport Scotland said: “Any decision regarding compensation would only be taken after full consultation with affected parties including workers’ representatives.”
He added: “We are investing £60million in the Caledonian Sleeper service to help drive up performance and improve service quality including capital expenditure on new sleeper trains.”
The RMT has claimed the disruption was likely to cost more than £300,000, branding it “a taxpayer-funded bung”.
Serco has clashed with the union over allegations about disconnected smoke detectors, faulty lighting and heating systems, the standard of air conditioning and a claimed lack of hot water in some coaches for hand washing.
RMT general secretary, Mick Cash, said his members simply decided “enough was enough” and they had no option to act “before someone is injured”.
Peter Strachan, managing director of Caledonian Sleeper, said he was extremely disappointed by the disruption – at one of the busiest times of the year.
The union has alleged that the dispute was caused by “penny-pinching on maintenance by Serco, which has allowed a number of major defects to rolling stock to deteriorate to a level where it is unsafe”.