The threat of industrial action on the railways is looming as ScotRail workers prepare to vote on whether or not to strike.

Guards are to be balloted after talks broke down in a row over driver-only operation.

The RMT union says it is opposed to any plans to extend driver-only operation, maintaining that guards should be in control of operating doors.

RMT general secretary Mick Cash said: "Any extension of driver-only operation is a clear attack on our members' hard-earned terms and conditions.

"RMT members should not have to face the risk of their role and responsibilities being reduced and undermined.

"There is also a very real threat to passengers of watering down and wiping out the safety - a critical role of the guard on ScotRail services. That is a lethal gamble with basic rail safety.

"RMT is in no doubt that our members will stand together and demonstrate the strength of feeling across the ScotRail network during this dispute. The union remains available for further talks."

Phil Verster, managing director of the ScotRail Alliance, said: "We have been informed by the RMT that they intend to ballot members for industrial action regarding driver-controlled operation.

"No formal proposals for DCO have taken place, and we are still at the stage of considering all options.

"We are keen to continue working with the RMT to find a constructive way forward as soon as possible, and one which will not affect our customers."