Cleaners working on the Tube have been demonstrating at City Hall demanding the mayor ensures they get a London Living Wage of £7.20 per hour.
The protest follows a series of strikes on the Tube last month which saw more than 700 members of the Rail, Maritime and Transport (RMT) union cease work.
The union said despite Mayor Boris Johnson’s promise of £7.45 hourly wages the cleaners are paid £5.50 by firms.
The cleaners are employed by four private contractors.
Activists from the women’s rights group Feminist Fightback have also joined the demonstration as a majority of the cleaners are women and migrant workers.
RMT general secretary Bob Crow said: “There are hundreds of cleaners working on the world’s most prestigious metro system being paid a pittance on contracts that the mayor is ultimately responsible for, and they need a living wage now, not jam tomorrow.
“Metronet is now under the mayor’s direct control, and three of its cleaning contracts are being renegotiated right now, but so far there has been not one word about the London Living Wage,” he said.
Mr Crow also alleged that striking workers faced intimidation as employers resorted to “gangster tactics” to get them back to work.
The allegations have been denied by Transport for London who said it was not aware of any intimidation.
A spokesperson for the mayor of London said: “The mayor believes Tube cleaners should receive the London Living Wage.
“Transport for London are working to ensure that this is implemented into Metronet cleaning contracts as has already been made clear to the trade unions.”
The RMT is also demanding improvements to holidays, sick pay and pensions.