Supermarkets and hotels paying below the living wage are to be "shamed" by a leading union in a new campaign to tackle low pay.
Unite said its drive will start in London, where many hotel and bar workers were being "exploited" by their employers.
Assistant general secretary Steve Turner told Unite's national conference in Liverpool that supermarkets should not wait to be shamed into action.
"We will begin our war on low wages in London, a city that is not sharing its wealth with the army of service workers who make it rich.
"When the next mayoral hustings comes around, Unite will organise hospitality hustings where the candidates will have the chance to say what they will do to stop the poverty pay and exploitation rife in the city's international hotels, fast food corporations and restaurant chains.
"Those high street names happy to spend millions avoiding their rightful taxes, but not prepared to pay hard working staff a wage they can live on will not be allowed to rest."
The living wage is set at £8.80 an hour in London and £6.65 elsewhere, compared with the national minimum wage of £6.31.