A row has erupted in France over the 1999 national census plans to include a sample survey on the ethnic origin of respondents.
The National Statistics and Economic Studies Institute, which organises the census, has traditionally not included such data.
Routine surveys often ask respondents where they were born but "it is very rare to ask them the birthplace or mother tongue of their parents," said Michel Jacod, head of the institute's demography department.
But a one in 50 sample survey of family history is expected to be included in the census.
One person in four in France is an immigrant or has at least one parent or grandparent who has immigrated in the past century. Official surveys, however, have never adopted ethnic classifications used in Britain and other countries. "The use of such categories is absolutely not in what we call the Republican tradition, which stresses assimilation, or at least integration, of foreigners," said Mr Jacod.
But demographers such as Mich le Tribalat, research director at the National Institute of Demographic Studies (INED), believe ethnic origins should be recorded to combat race discrimination. She found lack of information in the mid-1980s prevented her from studying how people from immigrant families fared compared with indigenous French.
Using data from the 1990 census she constructed ethnic categories that enabled her to demonstrate in 1992 that the unemployment rate for young people of Algerian origin was 40 per cent compared with 11 per cent for youngsters in the category she calls Francais de souche - of French stock. "At the time, the National Front was not very happy," she said.
But while she considers the category as simply defining "individuals born in France of parents born in France for purposes of comparison," it is a term that disturbs or enrages others working in the field who oppose widening the use of ethnic categories in state statistical studies. Ms Tribalat and INED have even been accused of having links with right-wing extremists, though she has co-authored a counter-attack against the National Front.
This month the unions at the statistics institute, CGT and CFDT, organised a conference attended by about 75 demographers, statisticians and academics to debate the ethics and dangers of including ethnically-based information in research.
Conference organiser Francis Judas acknowledged such data are necessary for certain studies, but warned that "beyond an ad hoc inquiry every few years for structural assessment we don't think it timely to measure racism at every opportunity."
But Ms Tribalat said that "those who do not want to see or talk about the diversity of the population of France allow the idea to flourish of a uniform France, a single people, and they therefore go in the direction of the National Front".