Workers on ScotRail are to stage a fresh wave of strikes in a long-running dispute over driver-only operation.

Members of the Rail, Maritime and Transport union will walk out for 48 hours from August 7, 24 hours on August 11 and over the weekend of August 13/14.

The union opposes any extension of driver-only trains and wants guards to be in control of operating doors, stating safety is at the core of the dispute.

Members of the RMT have already staged a series of strikes since the row flared, which the union said had been "solidly supported".

A spokesman said: "RMT has repeatedly attempted to engage in serious talks through Acas but progress has been blocked as the company have tried to pick and choose issues and divide and rule the workforce.

"As a result, the union executive has taken a further report from our negotiators and have decided that there is no option but to move forward with a new programme of industrial action."

RMT general secretary Mick Cash said: "Recent rock-solid strikes on ScotRail have been supported by the travelling public who understand that the staff are fighting for the basic principles of rail safety.

"In spite of this, Abellio/ScotRail continue to ignore the strength of feeling amongst their staff and passengers over the extension of driver-only operation. That is why we have no choice but to announce further strike dates."

The rail union has announced a series of public meetings and demonstrations in its ongoing campaign against driver-only trains.

Public meetings are planned for next month in Glasgow, East Kilbride, Perth and Dundee, to which the transport minister and ScotRail management have been invited.

The union will also stage a protest in Glasgow outside the Scottish Government's offices on August 8, and a demonstration outside the Scottish Parliament in Edinburgh on September 8.

ScotRail says 59% of customers already travel on a train where the doors are safely opened and closed by the driver, and insists that the job, pay and conditions of conductors is guaranteed.

A Transport Scotland spokesman said: "We are obviously extremely disappointed that the RMT have announced this new wave of rail strikes.

"The Scottish Government will continue to monitor our transport networks over the strike periods and take appropriate action to ensure that proper planning and contingency measures can be put in place to minimise any disruption."