SCOTRAIL engineering staff will be balloted over further strike action as ticket examiners and conductors prepare to walk out on Sunday, transport union RMT said today.

The union confirmed strike action over “equality between grades in payments for rest-day working” will go ahead this weekend.

Earlier this month, ticket examiners voted in favour of walkouts over the dispute.

While this weekend was due to be the last of six Sundays of strikes by conductors, workers will begin another six Sundays of action from May 9.

RMT said that it will shortly begin balloting engineering grades over the same issue of “workplace justice on enhanced payments,” calling on ScotRail operator Abellio to engage in talks.

General secretary Mick Cash said: “We now have the appalling prospect of poorly trained managers being drafted in without any experience to scab on RMT members’ jobs, regardless of the safety consequences.

“If Abellio and Transport Scotland think our members are going to be put off by this refusal to engage, then they know nothing of their own workforce and their resilience.

“RMT remains available for talks and it’s about time the company started acting responsibly and took up that offer.”

ScotRail has warned customers of expected disruption, claiming the action is “wrong” and “damaging.”

Head of customer operations Phil Campbell warned that “industrial action will have no impact on ScotRail’s position” on overtime pay increases.

Transport Scotland said they understood workers’ frustrations as “staff have been instrumental in keeping services moving for key workers.”

A spokesperson added: “We appreciate other grades are waiting on pay negotiations to restart, but we are unable to progress longer-term pay arrangements until we have more certainty of the financial outlook.”