Anti-poverty campaigners have been targeting Tesco shops in an attempt to pressure the company into paying staff the Living Wage.
Doctored food labels have been popping up in shops, calling for the company to give their employees a pay rise.
The calls come as new research from the Living Wage Commission, chaired by the Archbishop of York John Sentamu, found that the majority of people living in poverty in the UK are from working households.
The Living Wage is the minimum amount necessary to enable workers to provide for their own basic needs. The rate is currently at £8.80 in London and £7.65 in the rest of the UK. The National Minimum Wage is currently £6.31.
Working poverty and growing income inequality has been identified as an important electoral issue, and Labour have said they will "significantly" raise the minimum rate.
Rhys Moore, Director of the Living Wage Foundation, said one of the issues is that minimum wage rates of pay have become an acceptable benchmark of earnings for some employers, instead of the "absolute legal floor" it was intended to be.
A former Tesco worker has started a petition calling for the company to adopt the Living Wage, and the thousands of names will be presented at the company's AGM this Friday.
Former Tesco till worker and manager Amy Bradley said the company needs to improve pay as the current rates are not enough to survive and thrive on.
Research from the TUC said a breakdown of official figures showed that around 20% of workers across the UK were taking less than the living wage.
In some areas this number rises to almost 50%, with London and areas in the south of England being the areas where the most underpaid workers live.
Tesco said they already pay the Living Wage, if the benefits and rewards package offered to staff was included in the calculation. A spokesperson said:
Rhys Moore from the Living Wage Foundation called on Tesco to take the lead on the issue of poverty wages, and commit to raising the game across the retail sector.