The study, by the policy think-tank Tasc, estimates there are at least 500 public bodies or quangos. The report, which was seen by the Sunday Tribune, estimates that there is one quango for every 5,000 people in Ireland but says an accurate assessment of their nature, scale and significance is difficult to establish.

Four departments . . . health, justice, education and communications/marine . . . account for 50 per cent of all quangos.

In the last year alone the government set up six new bodies including the National Consumer Agency, a task force on active citizenship and an alcohol marketing monitoring body.

"The unplanned and ad hoc mushrooming of public bodies, combined with the lack of good information about them, is bad for democracy, " the report says.

There is also confusion about the status of many agencies. Tasc found that the government website still lists the Agency for Personal Services Overseas, which was abolished in 2004.

The report, to be published this week, also found that women make up only 25% of the membership of quangos, even though a 40% guideline was established in 1991.