Commuters are facing travel disruption as ScotRail workers go on strike in an ongoing row over driver-only trains.

The Rail, Maritime and Transport (RMT) union is staging the latest in a series of planned walkouts in a dispute with ScotRail.

The union has said it remains "rock solid and determined" in its industrial action.

A total of 18 routes have been cancelled while the frequency of a number of other services is reduced.

It's estimated that about 70% of services are unaffected. The 24-hour strike action on Sunday is due to run until 11.59pm.

Further walkouts are due to be held on July 10, 11, 14 and over the weekend of July 16 and 17.

Industrial action has already been held and the conciliation service Acas has been involved in trying to resolve the dispute but it remains deadlocked.

The union said it was defending its policy of no extension of driver-only trains (DOO) and for guards to be in control of operating doors.

The union has said it fears the introduction of driver-operated doors will "water down and wipe out the safety critical role of the guard on these ScotRail services".

RMT General Secretary Mick Cash said: "Despite the continuing and rock-solid action today it is extraordinary that Abellio/Scotrail choose to ignore the strength of feeling amongst their staff over the extension of DOO.

"That disgraceful and cavalier approach to jobs and safety on Scotland's railways is shameful.

"Our members on Scotrail stand determined and united in this fight for jobs and safety this morning and it is time for the company to ditch their ludicrous pre-conditions and start talking seriously about the whole range of issues at the heart of this dispute."

Transport Scotland has said its priority throughout the process has always been safety and encouraging a swift and satisfactory resolution to the dispute.

A statement on the ScotRail website said the strike is "totally unnecessary".

It read: "We will always schedule a second person on trains to serve our customers.

"Today, 59% of our customers travel on a train where the doors are safely opened and closed by the driver.

"The body in charge of regulating safety on the UK rail network - the ORR - say this is a safe way of working.

"And we've guaranteed all our conductors will keep their job, pay and conditions."