Leading experts on pre-school education are mobilising in London today against the new national curriculum for under-5s, which they warn risks “making children go backwards” in their development.

Steve Biddulph, the Australian educational psychologist and author, is among a series of high-profile speakers at a conference questioning the basis of the new statutory Early Years Foundation Stage Framework.

The Framework prescribes 72 early-learning goals for the under5s, ranging from the bland (“continue to be interested, excited and motivated to learn”) to the ambitious (“understand what is right, wrong and why”) and from the sweeping (“begin to know about their own cultures and beliefs and those of other people”) to the highly detailed (“use their phonetic knowledge to write simple regular words and make phonetically plausible attempts at more complex words”).

Mr Biddulph said last night that the highly structured approach of the new Framework filled him with horror.

He cited research from a ten-nation study of preschool education initiated by the late American psychologist David Weikart, which found that children’s language development slows down the more time they spend in forced group academic activities but speeds up the more free play they engage in. Similarly, children’s thinking and reasoning skills increase when they spent less time in whole group activities and more time in free play.

“Forcing learning destroys that learning. It makes children go backwards. The harm may well be lifelong,” Mr Biddulph said.

The Government insists that the new goals have to be made statutory to ensure that children from poor families get proper support regardless of the type of preschool childcare their parents use. Without this, they risk falling behind middle-class children, who get more learning support at home.

Mr Biddulph suggested that “high-quality programmes targeted at high-need communities” would provide a better approach to social equity. He gave warning that Britain was in danger of following the example of Australia, where there is a 50-point standard for childcare centres beginning with: “Every child is greeted by name when they arrive at the door.” “If you have to mandate that, or if its done by rote to fulfil the guideline, I think you’ve already lost the race. It leads to robotic behaviour,” he told The Times.

The childcare expert Penelope Leach, who will also address the conference, agreed that the best way to narrow the performance gap was through home visits to the most needy rather than by forcing an estimated 25,000 state, voluntary and private sector preschool providers to adopt the same goals.

Lilian Katz, Professor of Education at the University of Illinois, will point out that children who are pushed towards reading and writing at too early an age do less well in later years than those who have been eased into formal education through play. Boys in particular suffer from too heavy a focus on academic learning in preschool.

“Boys are growing in a culture where they are expected to be active and assertive, but when they are put in an academic regime at the age of 3, they become passive. They soon lose motivation,” she said.

Opposition to the new Framework has been growing since an article in The Times last November led to the creation of the Open Eye campaign by Richard House, senior lecturer in psychotherapy and counselling at Roehampton University.

Nearly 5,000 people have now signed a petition on the Downing Street website calling for a review of the Framework. Many of the campaigns supporters advocate the kind of approach used in Steiner or Montessori preschools, where children are allowed to learn and develop at their own pace.

Beverley Hughes, the Children’s Minister, dismissed the Open Eye campaign as unrepresentative, insisting that the majority of early-years providers and parents were in favour of the new Framework. She denied that the Framework was too rigid or inflexible.

“The Framework is completely play based. It leaves a great deal of discretion for staff to organise things as they see fit. We want the staff to be organised in their head every day about what they are going to do. But the children’s experience will not be structured,” she said.

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