The government says this confirms the success of its policy of recruiting more teachers and building more classrooms in popular schools - but critics say that it has been achieved at the expense of secondary schools, where class sizes are rising.

James Westhead reports

Labour promised that no five, six or seven-year-old should be in a class of more than 30 pupils by the end of the current Parliament in 2002 - a target later revised to September 2001.

According to figures published on Wednesday, there are now 180,000 pupils in classes with more than 30 pupils - compared with 365,000 last year and 485,000 the year before.

The average class size for older primary pupils is still rising

"When we came to power, almost half a million infants were being taught in classes of more than 30. Today the figure is a third of that," said the Education Secretary David Blunkett.

But the Conservative education spokeswoman, Theresa May, has accused the government of using statistics selectively, pointing to the increase in average class size for primary schoolchildren aged eight to eleven and in secondary schools.

"Tony Blair stood before the country and said class sizes will be lower. But as they prepare to boast about how they have supposedly fallen, they have in fact gone up," said Ms May.

The figures for eight to eleven year olds show that while the proportion of children taught in over-size classes has fallen - from 40% to 39% - the average class size has risen from 28.3 to 28.4.

John Dunford says that the gain for infants has been a loss for older children

In secondary schools, the most recent figures published earlier this year showed that average class size had risen to 22 pupils - the highest for a decade.

"The cost of government success on this one policy is an increase in the average class size for older children, more older children in classes over 30, a worsening of the pupil-teacher ratio," said John Dunford, general secretary of the Secondary Heads' Association.

Popular schools

But the government has defended its achievement in cutting class sizes for the youngest pupils, saying that it is not a manipulation of figures but a result of investment.

The Schools Minister Estelle Morris said that an extra £620m is being spent on a three-year programme which will recruit 6,000 extra teachers and build 4,200 classrooms.

The building and recruitment drives have allowed 15,000 extra pupil places to be created in popular, over-subscribed schools - with 3,000 places lost in unpopular schools where demand is low.

Ministers say this disproves claims that the curb on class sizes has also meant a curb on parental choice - and that their focus has always been on expanding popular schools.

That downward trend has prompted speculation that the government might feel able to set a new target, for getting the class sizes for those eight to 11 year olds to 30 or below - which would give Labour a useful boast to take into a possible early general election next year.