The National Primary Headteachers' Association (NPHA) accused the Government of being in an 'obscene rush' to get children doing academic work, in a submission to the biggest review of primary education in 40 years.
The Primary Review is a two-year Cambridge University study approaching its midway point. The first interim report will be published this week.
The NPHA report called for nursery and reception class 'fun learning' methods to be extended over the first year of primary school, at the least.
It said research showed that the Scandinavian practice of starting formal education later, at age seven, could produce better academic results in the long term. According to the report, play in teaching and learning would 'disappear entirely in the vast majority of schools' in England at the beginning of Year 1.
Peter Price, NPHA chairman and Liverpool headteacher, said that children 'learn better when they enjoy,' and that guided play was the best way to teach those starting school.
A spokesman for the Department for Children, Schools and Families said, 'The formal school starting age of five has served children well for decades and standards in our primary schools have never been higher. All the evidence - results, international comparisons - makes this clear.'
Further information: www.primaryreview.org.uk.