They insist it is vital for children to be taught to combat racism from the age of three if they are to function in a global world.
Charlotte Tagart, of the World Education Development Group (WEDG), believes staff are often wary of tackling racist statements from young children. "How do you present balanced information to children without undermining their parents?" she said. "There are a lot of practitioners who'd like to deal with comments, but they don't have the skills. We need to get the children to put themselves in somebody else's shoes. It's a building block for global citizenship."
Hetan Shah, of the Development Education Association charity, agrees. He would like to see one member of staff at every nursery trained in handling such issues.
"Attitudes do come about when we're very young, before we even consciously know what we're thinking," he said. "So the more work you can do on very young people, the better."
WEDG runs a scheme training early-years staff to challenge racist statements from pupils. When a three-year-old says, "I don't like black people", for example, staff should ask the child to repeat it, to confirm they did not mishear it. They then present pupils with a hypothetical scenario: imagine someone had said these things to a friend. How would they feel?
"Often, the children who have said negative things are the first to identify that this would make people sad," Ms Tagart said.
"But often, unfortunately, these issues get brushed under the carpet. It takes a lot of time and experience to know how to deal with them."
Staff at Seashells nursery, in the Isle of Sheppey, Kent, have taken the training. Since then, Julie Kairis, the deputy manager, has noticed that pupils are increasingly considerate and tolerant.
She believes all primaries and nurseries should send staff for similar training. "We're not a monocultural society," she said. "Children as young as three need to understand that they need to respect other people's beliefs and values."