They may still be in nappies and playing with sand and building blocks but many toddlers are already racists, nurseries have been warned. To stop prejudice from developing while children are still three years old, staff need to ensure that different racial groups "play together right from day one", according to Herman Ouseley, the former chairman of the Commission for Racial Equality.
Nursery staff should "discourage separate play" and "help children to unlearn any racist attitudes and behaviour they may have already learnt", said Lord Ouseley.
"It is important to consider whether patterns of play are consistently based on racial or cultural grounds," he writes in the latest issue of the journal Race Equality Teaching.
"If, for example, Muslim children nearly always play together and seldom play with other children, the question needs to be asked, 'Is there a reason for it that may relate to culture? Or apprehension? Or prejudice?'," said Lord Ouseley, the author of an influential report on the 2001 Bradford riots.
The recommendation that staff intervene to ensure that children mix goes further than current thinking and guidance, which concentrates on making sure nurseries cater to all ethnic groups.
Jane Lane, a co-author of the article and an early-years equality adviser whose publications are recommended by the Government's Sure Start scheme, said conventional wisdom that toddlers were "colour blind" was wrong.
"There is a view that children do not learn their attitudes until they are about five," she said. "But people in the early years know that children at a very early age - at the age of three - are categorising people. I am not talking about white children; I am talking about all children. Many, many are racially prejudiced, for all sorts of historical reasons."
Margaret Morrissey, the spokesman for the National Confederation of Parent Teachers Associations, said, however, that children did not generally notice colour until at least the age of six and that "artificial" attempts to force the issue could be detrimental.
"In all the time I have been involved in nursery education, since about 1975, I have never seen children segregating to play," she said.