Critics of the minister have reacted with cynicism, asking why it took a newspaper report to alert M Allegre to the practice of teaching French children separately - the subject of numerous reports and studies over the years.
M Allegre announced the inquiry, due to start work this month, the day after Le Monde published a widespread survey into racism in France - in housing, employment and education.
The newspaper cited several instances of apparent racial segregation. In one case, a child of Tunisian origin who transferred from nursery school to primary school found none of his former schoolmates in his new class; instead there were only "Chinese, blacks and Arabs". His white friends were grouped into the other first-year class.
Of three olleges (junior high schools) in one street in eastern Paris, the newspaper found that the first had 40 per cent of pupils of immigrant origin, the second 6 per cent and the third 26 per cent.
Professor Eric Debrabieux of the school of education at the university of Bordeaux II, who has spent five years studying the treatment of pupils of immigrant origin, said: "Faced with the mass arrival of young people who have not previously had access to a general education, school heads do everything they can to retain middle-class children by keeping them together."
The methods used may be subtle: middle-class pupils are steered into "difficult" subjects such as German or Latin, or offered sporting options such as tennis, while the less-valued children are directed toward the more common foreign languages and football. That gives the school the pretext to divide the children into different classes.