Cleaners demonstrated outside Whipps Cross Hospital in protest at plans to cut their hours.
Union Unison has warned that the proposals to cut 30 minutes from shifts of dozens of staff will reduce the cleanliness of the Leytonstone site and put patients at greater risk of picking up infections.
Workers were out in force at the protest yesterday evening, with many also angry that the cuts will reduce their low salaries yet further.
Private contractors Initial Facilities, a subsidiary of the Rentokil company, says the measures are part of a shake-up which will improve "productivity and efficiency".
It denies patient care would be at risk and that the measures are due to financial pressures.
A consultation with staff about the plans is currently on-going.
Initial employs around 300 staff at the Leytonstone hospital, including cleaners, porters and switchboard operators, and says only 36 will be affected by the proposed cuts.
Unison claims the figure is actually 41 and said it was only the first phase of a programme of cuts.
If approved, 30 minutes would be cut from seven-and-a-half hour full-time working days and three-hour part-time evening shifts.
Barts Health NHS, the trust which runs Whipps Cross Hospital, has previously refused to comment on the row.
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