The Taoiseach has said nobody needs to be fearful about filling in the Census form, as the information is kept strictly confidential.

Launching the publicity campaign for Census 2006, which takes place on 23 April, Bertie Ahern stressed that the information collected is for statistical purposes only, and would not be used by any other State agency.

The upcoming Census will provide indicators of the extent of the diversity of multi-cultural Ireland in 2006. For the first time, the Census will ask people to describe their ethnic or cultural background. The forms are available in 13 languages, including Irish and English.

There are also new questions this year on women's fertility and on voluntary work.

The Central Statistics Office is particularly keen to ensure that everyone completes a form, even those whose legal status in this country is unclear.

1.5 million forms are to be distributed to households around the country, at a cost of €50m.

Preliminary results giving the overall population are expected within three months, and the full break-down of the figures should be available within one year.