Dozens of trains a day are running without planned refreshment trolleys, with the gaps said to have reached record levels,
Travellers on around 30 services yesterday were unable to buy food and drink on board, including between Edinburgh and Inverness, and Aberdeen and Glasgow.
That followed some 40 trains without catering last Thursday and around 50 last Friday.
ScotRail said there would be “improvements” within two weeks once vacancies had been filled.
It said the shortage had been caused by staff moving to better-paid posts within the company, such as station staff. Ironically, these posts are part of a remedial plan to improve ScotRail performance.
The operator can be fined up to nearly £5,000 if there is no catering on 90 per cent of trains where trolleys should be provided.
Angry passengers have taken to social media to complain about the service failures.
Highland Liberal Democrat councillor Angela MacLean, from Dingwall, tweeted: “The catering is cancelled so often I, like many others, bring my own now.” Fed-up Mark Johnston tweeted: “Every time I use rail at the moment I expect to have no catering.”
Jordan McBrearty tweeted: “No catering trolley on a 2 hour and 40 minute train journey. What a joke.”
Anthony Smith, chief executive of watchdog Transport Focus, said: “Passengers will be disappointed a number of services are still without catering due to staff shortages and will now want a clear plan of action from ScotRail, setting out exactly when they will get the promised improvements.”
ScotRail is advertising for train hospitality assistants based in Aberdeen, Inverness, Edinburgh and Glasgow, paid £19,611 for a 36-hour week.
A Transport Scotland spokeswoman said: “ScotRail know our expectations round having robust recruitment in place to ensure they continue to deliver their obligations, including on-board catering services.
A ScotRail spokesperson said: “Customers will see improvements within the next couple of weeks as staff training completes.
“They’ll then see further improvements once any remaining vacancies are filled and new staff are in place.
“Feedback from our customers tells us they would like to see more food and drink services and that’s exactly what we’re trying to provide.”