Liverpool City Region train users are set to be hit by nine days of industrial strikes across the Merseyrail network over the festive period.
The Rail and Maritime Transport workers union (RMT) has said it will instruct guards, standard managers and train drivers in the region not to book on for every Saturday over November and December.
The announcement comes amid a long-running dispute surrounding how a new fleet of Merseyrail trains will operate when they arrive on the network from next year onwards.
The strike days would include key dates around Christmas in New Year, such as Saturday December 14, Saturday December 21 and Saturday 28 December 2019, the Liverpool Echo reports .
The row has focused on the role that guards will play on the trains - and how the doors to the new trains will be operated.
Last year it was thought a breakthrough had been found in the ongoing talks after Merseyrail agreed 'in principle' to place a second safety-focused member of staff on board the new trains.
But the union remains unhappy at plans for the train drivers to be in charge of opening and closing the train doors during journeys.
In July - a wave of six new strikes was announced, but a number of these were called off after what were described as 'positive talks' between the two sides - brokered by Metro Mayor Steve Rotheram.
But writing on the RMT website today, the union's General Secretary Mick Cash said: "Our discussions with Merseyrail on the Role of the Guard have been ongoing and your negotiating team have continued to attempt to carry out the instructions of the NEC, reporting back in detail at all key points in what has been a drawn out negotiating process at ACAS."
Mr Cash said the union is today entering into an 'avoidance of disputes' meeting to discuss the various options and the dispute.
But he added: "Therefore, to focus the minds of management and to guarantee a safe and secure railway the National Executive Committee is instructing all Merseyrail Guard, Guard Standard Managers and Train Drivers not to book on for any shifts that commence between: -
00.01 hours until 23.59 hours on Saturday 2nd November 2019
00.01 hours until 23.59 hours on Saturday 9th November 2019
00.01 hours until 23.59 hours on Saturday 16th November 2019
00.01 hours until 23.59 hours on Saturday 23rd November 2019
00.01 hours until 23.59 hours on Saturday 30th November 2019
00.01 hours until 23.59 hours on Saturday 7th December 2019
00.01 hours until 23.59 hours on Saturday 14th December 2019
00.01 hours until 23.59 hours on Saturday 21st December 2019
00.01 hours until 23.59 hours on Saturday 28th December 2019
The union said that it will also instruct members not to work any overtime or rest days, from 00.01 hours on Sunday 3rd November 2019, until further notice.
Mr Cash added: "Once again I would like to thank you all for your continued support for your union throughout this dispute and urge you to continue to stand shoulder to shoulder with your colleagues on the days of action.
"Management must be left in no doubt that we will do everything to ensure a safe and secure railway and will not allow the Safety Critical Role of the Guard be decimated by a company putting profit before safety.
"The Role of the Guard must be defended."
Merseyrail was contacted for a response.
