Tube station cleaners have begun a 48-hour strike in a dispute over pay.
The Rail, Maritime and Transport (RMT) union announced last week members working for contractors Initial and ISS would walk out from 5.30am this morning.
The strike comes just days after Tube drivers took industrial action in a row over bank holiday pay.
The Boxing Day strike across the capital's Tube network caused disruptions to the Northern, Piccadilly, Victoria, Jubilee and Bakerloo lines.
But London Underground asset performance director Philip Hufton has reassured commuters that today’s strike is not likely to affect train services.