The government must "get to grips" with the level of absence among public sector workers, a senior business leader has urged.
Long-term illness accounted for 57% of public sector absence
Sir Digby Jones, the director general of the CBI, warned that the problem was undermining services.
Research by the CBI showed that on average employees in the public sector took off three days more than those in private companies last year, he said.
But the TUC dismissed the claims and challenged the findings.
Early figures from the business group's annual survey of absence at work revealed that public sector workers took an average of 9.1 days off in 2004 compared with 6.4 in private companies.
One of the worst government departments for absence was the Department for Work and Pensions.
The poll of 500 organisations showed that public sector absence cost the economy £4.1 billion last year.
The figure would be cut by £1.2 billion if the absence rate was the same as in private firms, said the CBI.
The findings also revealed that the public sector accounted for 40% of the number of working days lost - long-term absence, lasting 20 days or more, was responsible for 57% of the total.
The CBI said its research, due to be published in full later this week, cast doubt on public sector efficiency targets.
Sir Digby said: "For the UK economy to succeed, both the private and the public sector must pull their full weight.
"The private sector has no option in a world where global competitiveness is all.
"It is high time the public sector delivered for the taxpayer on the same basis."
'Injuries on duty'
But the TUC challenged the figures, claiming that public sector workers were less likely to take short periods off work compared to their colleagues in the private sector.
TUC general secretary Brendan Barber said: "The CBI wants us to think that public sector workers are too ready to throw a sickie and take a few days off whenever they feel like it.
"But more serious analysis of absence statistics shows the exact opposite.
"The average figure for public sector workers is higher only because more public sector workers take long-term sick leave, much of which will have been caused by injuries on duty."