Cleaners on London Underground are to launch a 48-hour strike in a dispute over an Olympic bonus payment, Press Association reported.
Members of the Rail Maritime and Transport union employed by private contractors will walk out at 5.30am, mounting picket lines outside Tube stations including Stratford, close to the Olympic Park.
RMT general secretary Bob Crow said: "With the eyes of the world on the London Olympics the many millions enjoying the events around the globe must not forget the London transport cleaners on minimum pay rates doing some of the dirtiest jobs in often appalling conditions with no Olympics recognition and reward whatsoever.
"It is these same staff who have played a key role in keeping services clean and safe who are now forced again by their employers to take action for a living wage and recognition of their Olympics efforts."
Phil Hufton, asset performance director for London Underground, said: "This industrial dispute is between Initial and its staff. We have reviewed our staffing plans and have already put contingencies in place. We anticipate no impact on London Underground services as a result of this industrial action."