The incomes of lower paid shop workers is falling further and further behind other workers, according to the trade union Mandate.
The union says that over the last five years the income gap between retail workers and public sector workers has widened substantially.
The union’s General Secretary John Douglas said: "The pay of local authority labourers increased by 57.5 per cent since 2000 compared to 37.1 per cent for Tesco workers and 33.3 per cent for Penney’s staff."
Mr Douglas said: "The growth in pay rates for lower paid workers in the civil service was also higher than for retail workers, with clerical officers and service attendants gaining increases of 43.5 per cent and cleaners achieving rises of 43.7 per cent.
Speaking at an Irish Congress of Trade Unions’ (ICTU) Conference in Belfast, Mr Douglas said that future trade union movement strategy around pay would have to address this growing gap.
He said "In hard cash terms, if Tesco workers had secured the same pay increases as local authority labourers over the last five years, those currently on €427.50 per week would be on €490.90 – €57.50 or 13.5 per cent more."
Mr Douglas said that while Ireland is the 12th most prosperous country in the world, a growing number of the country’s workforce is living below the poverty line.
"In 2001 almost one in five people in Ireland facing income poverty were working for a living.
"The proportion of working people who were income poor increased by over 300 per cent in the three years from 1998 to 2001, rising from 2.6 per cent of the workforce to 8.1 per cent. And the gap is only getting bigger," he said.