Managers' pay up €130 a week - while workers get just €2 extra
Pay for managers and professional workers rose by €130 a week in the past five years, but lower-paid staff only received an extra €2.
A new report by Unite, 'The Truth about Irish Wages', also reveals that the highest-paid private sector workers earn almost four times as much as the lowest-paid employees.
The union said its research proves that the economic recovery is a myth for thousands of workers who earn less than their counterparts in the EU.
It also reveals Irish workers' "compensation", which includes gross wages and employers' PRSI payments, is 6pc below the average in 15 EU countries.
Bin collectors' wages are among the worst, at 28pc below EU levels, while hotel and restaurant staff are on 20pc less and retail workers on 18pc less.
The report says managers and professionals enjoyed average wage increases of 11pc between 2010 and last year, but office, sales and service staff pay rose by just 1pc, or €6. Despite high levels of national income and profits, wages for production, craft, transport and manual workers increased by just €2 a week, or 0.3pc.
Ireland has the second-highest level of wage inequality, behind Portugal, out of 15 EU countries when it comes to the difference between the lowest and highest paid.
The report measures the ratio of the earnings of the top 10pc of earners compared with the lowest 10pc. It found wages for the top earners are nearly four times those of the lowest paid.
In the UK, the best paid earn 3.5 times what the lowest-paid earn. The highest ratio is in Portugal, where the top earners get over four times more, and lowest is in Sweden, where the highest-paid earn twice as much.
The report says average wage rates do not tell us how equal wages are. While there may be a high average wage in a country, it may still have a substantial number on low pay.
Unite Regional Secretary Jimmy Kelly said Irish wages are 18pc below average compared to northern and central European economies, and 24pc below average compared to other small open economies. He said low wages depress the economy because they affect domestic demand and the tax take.
"One of the most striking features of the research is not only that Irish wages are low in European comparison, but also that inequality is so high," said Mr Kelly. He said more unequal societies perform poorly on issues including mental health and life expectancy.
Unite's Education and Politics Officer, Brendan Ogle, said low pay is compounded by low levels of employers' social insurance, which mean workers have to pay more for services including healthcare.
The union wants an increase in employers' social insurance to fund improved services and income supports, and raise wages for the low paid through Joint Labour Committees.