Official figures show that average weekly earnings in the first three months of this year were down 3.8% from the same period last year, with public sector earnings falling more sharply than those in the private sector. The fall is much bigger than the 0.4% drop shown in the last quarter of 2009.
Average weekly earnings were €682.91 in the first quarter, down from €709.55 a year earlier. The CSO said the fall was due to a 1.5% drop in average hourly pay and 2.2% fall in the number of hours worked.
Weekly earnings in the private sector were down 2.8% from a year earlier, while earnings in the public sector dropped by 5.5%, as the effect of pay cuts introduced in last year's Budget took effect. The CSO's figures do not take account of the public sector pension levy introduced in March last year.
Average pay fell in 11 of the 13 categories, with the biggest drop of 9.1% in the education sector. Transportation and storage pay fell 7.3%.
Smaller and bigger companies - those with fewer than 50 and more than 250 workers - recorded similar drops of 3.9% and 3.6% respectively, with a smaller fall of 1.7% in firms with between 50 and 250 workers.
Average pay per hour in the private sector fell by 0.4% to €19.80, while in the public sector the drop was 3.7% to €28.87.
The CSO says average labour costs - which take other factors as well as pay into account - fell by 2.2% over the year to €25.46 an hour.
Separate CSO figures show a strong increase in the volume of industrial production in July. The Central Statistics Office said production in July was 12.4% higher than the same month a year earlier.
The rise was led by the modern sector - which includes technology and chemical companies - which showed a 17.3% annual increase. Production of pharmaceutical products jumped by more than 20% over the year. The traditional manufacturing sector was up 3.2% over the same period.
For the three months from May to July, production was 7.5% higher than in the previous three months.