A fresh round of rail strikes will see Scottish services crippled as a third union confirmed September dates for industrial action. 

Tens of thousands of Network Rail employees and staff at 14 train operators are to walk out on September 15 and 17, the Rail, Maritime and Transport (RMT) union has confirmed. 

The confirmed dates follow separate strike announcements from both Aslef and the Transport Salaried Staffs Association (TSSA). 

While the RMT action is likely to have the biggest impact on ScotRail services, disruption is also expected on September 26 as TSSA members at nine train operating companies and Network Rail walk out.

Members of the Aslef union at 12 companies will also take industrial action on Thursday, September 15.

RMT general secretary Mick Lynch warned the industrial action will continue "as long as it takes".

The union said more than 40,000 of its members will strike, warning it will “effectively shut down” the rail network.

Talks between the union and rail industry have been ongoing but there has been no breakthrough or new offers from either Network Rail or the operators, the union said.

Mr Lynch said: "Our members have no choice but to continue this strike action.

“Network Rail and the train operating companies have shown little interest this past few weeks in offering our members anything new in order for us to be able to come to a negotiated settlement.

“Grant Shapps (Transport Secretary) continues his dereliction of duty by staying in his bunker and shackling the rail industry from making a deal with us.

“We will continue to negotiate in good faith, but the employers and Government need to understand our industrial campaign will continue for as long as it takes.”