Guards and drivers from the RMT union have reiterated their intention to strike on the Southern Rail network next week.
The RMT claims it took the decision because it has been "left out" of ongoing talks between Southern, the unions and the Department for Transport aimed at resolving the ongoing impasse.
Aslef - the other union involved in the ongoing Southern stand-off - called off next week's walkout on Tuesday (January 17) in return for the promise of fresh talks.
Southern has said it plans to run a full service on the network next week, although it remains to be seen how this stance will be affected by the RMT's declaration.
Strikes have blighted the Southern network since February last year, bringing misery to thousands of commuters in London and the south-east and leaving huge queues at pivotal transport hubs such as Clapham Junction and London Victoria.
The unions argue that Southern's plan to move to driver-only operated trains, and thus remove the guards from its service, is dangerous given the huge number of passengers who use the network. Southern, however, believes Aslef and the RMT have been unreasonable in their repeated walk-outs and have rejected reasonable compromise proposals.