A union has announced 27 days of rail strikes during December and on New Year's Day as part of a long-running dispute over train guards.
The Rail, Maritime and Transport (RMT) union said its staff at South Western Railway (SWR) had been left with "no choice" but to take industrial action.
The union said the dispute would continue for as long as SWR "refuse to give assurances" on the role of guards.
SWR said it was "extremely disappointed" by the planned strikes.
A spokesperson for the company added: "The deliberate targeting of services up to, and during, the Christmas period is typical of the lack of concern the RMT continue to have for our customers."
The union has told its members not to book on for duty:
- From 00:01 GMT on Monday 2 December until 23:59 on Wednesday 11 December
- From 00:01 on Friday 13 December until 23:59 on Tuesday 24 December
- From 00:01 on Friday 27 December 2019 until 23:59 on the 1 January
RMT general secretary Mick Cash said: "At the last meeting we held with SWR, principles in agreements were made in good faith with the company's negotiating team and we now feel hugely let down again.
"As long as the company continues to refuse to give assurances on the future operational role of the guard, we will remain in dispute.
"I want to congratulate our members on their continued resolve in their fight for safety and the role of the guard on SWR.
"It is wholly down to the management side that the core issue of the safety critical competencies and the role of the guard has not been agreed."
'Keep customers moving'
In a statement, SWR said it has offered to keep guards on all trains and the union was "purely focussed on keeping control of train doors in a misguided attempt to hold power over the industry".
It added: "Whilst we have shown commitment to the role of the guard by introducing over 80 additional guard roles since the start of our franchise, the RMT do not have the long-term interests of either our customers or our colleagues, including their members, at the heart of their actions.
"We remain committed to finding a solution that will help us build a better railway for everyone.
"We will do everything we can to keep customers moving during strike action."