Passengers in the north of England are to face further major disruptions on train services after talks to avert more strikes collapsed.
Northern Rail and the RMT union have been involved in a long-running dispute over guards on trains.
The union said that walkouts on Northern, which have affected trains between Blackpool, Preston, Manchester and Leeds, will now continue every Saturday in December.
The union said it was “sick of being treated with contempt” by National Rail and blamed it for the breakdown in talks at the conciliation service Acas.
The walkouts by members of the RMT union are the latest in the dispute with Northern over its plans last year to extend driver-only trains, which would lead to a shift of responsibility for closing train doors from conductors to drivers. The RMT has raised concerns over the impact of driver-only trains on passenger safety.
Related: Northern rail compensation scheme to include non-season ticket holders
On each of the strike days - which are planned for 8, 15, 22 and 29 December - Northern will run just under 30% of its normal service.
Northern said that all options would be “considered” over the role of a second member of staff on its services.
RMT general secretary Mick Cash said that it was “clear” that the Acas talks were “nothing but a stunt” to “hoodwink the union into suspending action”.
“It was clear that they were either unwilling or unable to address the union’s position on the three key points we have set out and the fundamental issues at the heart of the dispute,” he added.
Richard Allan, the deputy managing director at Northern, said that Northern approached the meeting with an “open mind” and made it clear it wished to continue discussions.
Related: Why I refuse to pay January’s unfair new train fares
“Any customer who needs help with access, personal security, information, ticketing and so on will have a member of staff, in addition to the driver, on board trains to help them,” he said.
“On behalf of customers and stakeholders, and in the spirit of working together, Northern would welcome RMT postponing its planned industrial action. We look forward to further talks at Acas,” he added.
This article was written by Molly Moss from The Guardian and was legally licensed through the NewsCred publisher network. Please direct all licensing questions to email@example.com.
Free Newsroom email alerts
Register for daily/weekly email alerts with news from The Financial Times, Forbes, Reuters, The Economist and more.