The Pre-School Learning Alliance is to present a report to a conference in London on Wednesday claiming that the government's plans for a nursery years' curriculum would put unnecessary pressure on infants.

This setting of targets for three to five-year olds could lead to symptoms of anxiety, such as tantrums and bed-wetting, rather than achieve accelerated learning, says the report.

Margaret Hodge says learning and playing can go hand in hand

The government has put forward proposals for a "foundation" stage for pre-school children, which would set "learning goals" such as being able to write their own name and count up to 10.

This emphasis on education would be at the expense of allowing children the freedom to play and would put pressure on infants without any evidence that it helps children's long-term development, argues the Pre-School Learning Alliance.

"Effectively, children now start school at four without any evidence to support the efficacy of such a change. There is no compelling rationale for children starting school at four and there are increasing fears - on the part of concerned parents and among early years educators - that it may actually be harmful," says the Pre-School Learning Alliance's report.

"Young and vulnerable children are often intimidated by an early start to their schooling and may revert to bed-wetting, nightmares or show other classic symptoms of stress."

Rather than improving the abilities of children entering the formal years of learning at primary school, the National Association of Primary Education has cautioned that "a lowering of the standards achieved in primary education could well result".

Education minister Margaret Hodge, who will address the conference, said the targets put forward for early years' learning were not excessive and did not exclude play.

"Play, care and education are seamless. They're not different for children and learning can be fun," she told BBC Breakfast News.

Giving the example of learning a nursery rhyme as an activity that could combine pleasure with finding out about numbers, she said the government's proposals were aimed at ensuring "appropriate" teaching for the early years.

Three-year-olds would not be under pressure to learn lessons that were beyond their reach, she said, but would be encouraged with basic skills such as speaking.