SCOTRAIL services are set to be crippled as rail workers stage a fresh strike in a bitter dispute over pay, jobs and conditions, threatening new chaos at the height of the summer holidays.

Members of the Rail, Maritime and Transport union (RMT) at train companies and Network Rail will walk out in a UK-wide stoppage for 24 hours on July 27.

Union leaders made the announcement after rejecting a new offer from Network Rail which they described as “paltry”.

The offer was for a 4% pay rise backdated to January, another 2% next year and a further 2% conditional on achieving “modernisation milestones”.

The stoppage is an extension of the three-day stoppage in which ScotRail when 50,000 staff walked out.

It left only five ScotRail routes remaining in service. All were in the central belt of Scotland and with the last train departing well before 6.30pm.

The strike also hit cross-border services. Only around 20% of services were running with services operating on the five routes between 7.30am and 6.30pm on each of the strike days.

It marks a continuation of an ongoing UK-wide dispute with Network Rail -which owns the UK's rail tracks, stations and signals – over plans to axe hundreds of critical maintenance jobs.

RMT said it was the biggest outbreak of industrial action in the industry in a generation.

ScotRail said it was assessing what the extension of the strike would mean in terms of services and that it will let customers know as soon as possible.

But the train operator said the level of disruption is likely to be  similar to the previous strike action.

The strike will have a widespread affect on ScotRail services because those involved int he industrial dispute are safety-critical workers, including signallers employed by Network Rail and are crucial to keeping trains running.

It comes as an emergency timetable which has cut services by up to half due to staff shortages remains in place across the Scottish network in a separate ScotRail dispute over pay with the train drivers union Aslef. A pay offer has been agreed by train drivers, but the curtailed timetable remains in place.

The RMT said it has yet to receive a pay offer or guarantees over job losses from the train operating companies (TOCs).

The RMT said it will be consulting other unions that have delivered mandates for strike action in the coming days, amid talk of co-ordinated walkouts.

HeraldScotland: ScotRail has warned passengers to expect severe disruption

Members of the drivers’ union Aslef and the Transport Salaried Staffs’ Association (TSSA) at train companies have backed industrial action in recent days.

RMT general secretary Mick Lynch said: “The offer from Network Rail represents a real terms pay cut for our members and the paltry sum is conditional on RMT members agreeing to drastic changes in their working lives.

“We have made progress on compulsory redundancies, but Network Rail are still seeking to make our members poorer when we have won in some cases double what they are offering, with other rail operators.

“The train operating companies remain stubborn and are refusing to make any new offer which deals with job security and pay.

“Strike action is the only course open to us to make both the rail industry and Government understand that this dispute will continue for as long as it takes, until we get a negotiated settlement.

“The public who will be inconvenienced by our strike action need to understand that it is the Government’s shackling of Network Rail and the TOCs that means the rail network will be shut down for 24 hours.”

The union says Network Rail is planning to cut at least 2,500 safety critical maintenance jobs as part of a £2 billion reduction in spending, including hundreds north of the Border.

Meanwhile, workers have been subject to pay freezes and changes to their terms and conditions.

Network Rail union workers will strike from 2am on Wednesday July 27 for 24 hours. Other train operator workers will take action from midnight.