Census workers from across Japan will begin collecting forms from households today to determine the nation's population and their occupations.

The government conducts a census every five years, although research as extensive as Sunday's is only carried out once every decade. This year's form contains 22 questions -- five more than in the previous survey.

On Sunday, about 830,000 census workers will begin collecting the forms, which were distributed in September.

The Management and Coordination Agency, in charge of organizing the census, has for the first time drawn up a manual for census workers instructing them on ways of protecting respondents' privacy.

Preliminary results of the survey, giving a breakdown of male and female populations and number of households, are scheduled to be released in late December. The data is to be used for a review of constituencies for Diet and local assembly elections.

Japan has been conducting nationwide censuses every five years since 1920 and Sunday's will be the 17th to date.

The census is in line with a United Nations call for countries to confirm their population levels and housing situations for the start of the new millennium.