Unions have questioned official figures showing an 8% gap in the average hourly pay of public and private sector workers, warning that the figures could now be "widely misused".
The Office for National Statistics admitted that comparisons were "not straightforward" because of differences in the types of jobs, adding that the public sector was made up of a higher proportion of skilled professions and older employees.
The public sector workforce also had more people with a degree or equivalent qualification, at 40% compared with 25% in private firms.
Neil Carberry, the CBI's director for employment, said: "These average pay figures do not make direct comparisons between specific job salaries in each sector. Nevertheless, it is clear that public sector pay is still considerably higher than pay in the private sector.
"We need to ensure that public sector salaries reflect local labour market conditions, by putting pay decisions into the hands of individual employers at the local level."
Civil service union Prospect warned that the data will be taken out of context by coalition politicians to continue their "attacks" on public sector workers.
Head of research Sue Ferns said: "If public sector earnings are to be put under the spotlight, this should be done on the basis of like-for-like data - not the limited comparators provided by the annual survey of hours and earnings."
Unison said the report "masked the reality" of low pay and the ongoing pay freeze for hundreds and thousands of people working for public services.
General secretary Dave Prentis said: "Don't let anyone be fooled into thinking that public sector workers are enjoying high wages. There are a lot more highly skilled, older and well-qualified staff working in the public sector, that skews the figures and masks the reality of low pay for hundreds and thousands of public service workers.
"Millions of public service workers are being hit by the Government's pay freeze. Local government workers are in the middle of a three-year freeze and even the lowest paid have not been given the £250 promised each year by George Osborne."