Figures from the Central Statistics Office show that the number of people out of work in the final quarter of last year jumped by almost 70% compared with a year earlier.
The CSO's quarterly national household survey also showed that the number of people at work in the economy fell by 4% from a year earlier to just over two million. This was the largest annual fall in employment since the survey started in 1975.
There were 170,600 people unemployed in the final quarter of last year, an increase of 69,600 or 68.9% from a year earlier. Male unemployment almost doubled in the period - up 85%.
The unemployment rate rose to 7.7% of the workforce, from 6.4% in the third quarter of 2008.
The CSO said the employment rate among people aged between 15 and 64 fell back to just under 66%, back to a level last recorded in 2004.
A breakdown of the figures showed that full-time employment fell by 93,900 over the year, with the biggest fall of 48,800 in construction. The wholesale and retail sector lost 14,000 jobs.
The number of non-Irish people working fell by 13,300 to 316,000. The number unemployed rose by 13,300 to 33,300, with people from the new EU states accounting for 7,500 of the increase.
