Workers on London's Docklands Light Railway are to stage a 48-hour strike over a "comprehensive breakdown" of industrial relations.
Members of the Rail, Maritime and Transport (RMT) union working as cleaners, security staff and travel safe officers will walk out from 5.30am on Thursday February 1.
The workers, employed by contractor ISS, took strike action on New Year's Eve, but the union said no progress had been made over pay and other issues.
RMT general secretary Mick Cash said: "We are supporting our members' further strike action in a bid to force management to properly adhere to the agreed negotiating machineries and stop trying to impose fundamental changes to working conditions.
"RMT reps have continually chased management to resolve the dispute but the company are blatantly ignoring the union's concerns.
"We are expecting further solid support in this dispute."