Huge changes to train timetables have resulted in rail staff being verbally abused by commuters.
Rail staff have faced fury from passengers angry at delays and cancellations to services after the new timetables came in this week, according to their union.
The Rail, Maritime and Transport (RMT) union said frontline staff have been taking the "full force" of frustration caused by disruption to Govia Thameslink Railway (GTR) trains.
The union said it had received numerous reports of staff being verbally abused, especially when services have been cancelled.
GTR's Southern and Thameslink franchises have seen services disrupted since the new timetable was introduced, with the RMT dubbing the start of the week as Meltdown Monday.
RMT general secretary Mick Cash said: "The vast majority of passengers know that the ongoing timetable problems in the wake of Meltdown Monday are down to the train companies and not the staff, but some lash out from sheer frustration.
"There is no excuse for that whatsoever and the union will not tolerate a situation where our members at the sharp end are effectively being deployed as human shields by a remote and incompetent management.
"This week's disastrous new timetable roll-out just further proves that GTR and Northern are not fit to run a railway and need to be taken out of the hands of the profiteers and be brought under public control."
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