The operator revealed it has begun training managers and supervisors to replace union staff as conductors in the event of a strike. News of the contingency plan sparked angry accusations by the leader of the Rail, Maritime and Transport Union (RMT), Bob Crow, who said the company was “spoiling for a fight” rather than trying to reach a negotiated settlement.

The RMT is due to meet ScotRail managers next Wednesday to discuss its opposition to using drivers – as opposed to conductors – to operate doors on trains that will run between Helensburgh and Edinburgh following completion of the £300 million Airdrie-Bathgate rail link later this year.

Mr Crow said ScotRail had been “deliberately provocative” ahead of the meeting. “It is clear that, rather than accepting that the key financial argument for the unsafe option of driver-only operations on the new Glasgow route has been demolished, ScotRail are actively spoiling for a fight,” he said.

The RMT’s campaign against such operations was revealed by The Herald last October and the likelihood of industrial action has grown in the intervening months, sources on either side of the dispute concede.

About two-thirds of ScotRail services currently use drivers to operate doors alongside ticket inspectors, a practice that has been in place for more than 20 years. The company claims it would cost £1.4m to convert the Helensburgh to Edinburgh trains to have conductors, delay their introduction and add a further £300,000 a year in staff costs.

Transport Minister Stewart Stevenson, who met with the RMT on Tuesday to discuss the dispute, said he was “not aware” of evidence that driver-only operations were unsafe but asked the union to provide further information.

ScotRail confirmed that dozens of managers and supervisors were being approached to go on training courses to help mitigate the effect of any industrial action. A spokesman added: “We hope that the meeting with the RMT will have a positive outcome and that the union will not escalate its campaign, which boils down to it trying to dictate who opens and shuts the doors on trains.”

“In the meantime, we are putting our customers first because, despite all our efforts to avoid industrial action, there is a possibility that it will happen.

“Our protective plans are designed to provide the travelling public.”