Talks aimed at averting a five-day strike by workers on Southern Railway are due to resume today.
Officials from Southern's owners Govia Thameslink Railway will meet again with the Rail, Maritime and Transport union under the chairmanship of the conciliation service Acas.
Two days of talks have already been held to try to resolve a dispute over the role of conductors.
The union has called the five-day strike from Monday if the deadlocked row is not resolved.
There was little indication if any progress has been made.
The company is also facing the threat of industrial action by two other rail unions in separate disputes over ticket office closures and claims of a breakdown in industrial relations.