The Irish Congress of Trade Unions has described an IBEC survey on absenteeism released this morning as 'bogus'.
The employers' group said absenteeism was costing Irish business around €1.5 billion a year.
IBEC said around 14 million working days were lost each year, averaging almost eight days per employed person.
A survey of 557 firms found that the problem was at its worst in large companies and in the manufacturing sector.
The average rate of absence is 3.4%, but almost a third of companies had an absence rate of 4% or more.
One eighth of companies cited alcohol-related illness as being a cause of short term absence for males.
IBEC said increasing long-term absence levels are mainly due to an ageing workforce.
Launching IBEC's new guide to managing absence, IBEC director Brian Geoghegan described it as a serious social and economic issue.
He said that apart form its obvious impact on particular workplaces, absence affected the wider economy through the loss of potential output and the increased spend on social security.
But ICTU general secretary David Begg said a survey of 16,000 EU workers found Irish employees take the second lowest number of sick days in the 15 member states.
He urged IBEC to study why Irish workers have the lowest holiday entitlements in Europe or are unable to take parental leave because it is unpaid.
