One in three East Sussex primary school pupils is being taught in a class of more than 30, Government figures show.

The county has the worst rate in the country for crowded classrooms, despite an overall decline in average class sizes.

Hundreds more pupils in Brighton and Hove and West Sussex are also being taught in classes of more than 30 pupils.

Ministers have hailed massive improvements in the teacher-pupil ratio across the country since Labour came to power.

In East Sussex primary schools, they have fallen from 28.2 to 27.5 between 1997 and 2004. In West Sussex they have dropped from 26.8 to 26.4.

But the overall average disguises dozens of schools which still have classes of 31 or more pupils.

Figures from the Department of Education and Skills reveal 27 per cent of East Sussex classes, educating 32 per cent of primary pupils, fall into this category, the worst rate in the country.

In West Sussex, 15.6 per cent of pupils are taught in the 12.8 per cent of classes with more than 30 pupils.

And in Brighton and Hove, 19.3 per cent of classes, containing 23 per cent of pupils, have more than 30.

Nationally, 15.2 per cent of pupils are taught in classes of 31 pupils or more.

Edward Davey, the Liberal Democrats' education spokesman who dug up the figures, said: "It is totally unacceptable that after eight years more than 500,000 primary school children are in classes of over 30.

"These shocking figures show just how badly the Government has failed to get the basics right.

"Some areas in England are suffering with a third of primary school classrooms packed with more than 30 kids at a time.

"Despite what ministers claim, parents in those areas know that Labour is failing their children.

"Large class sizes harm standards, affect discipline and are a major barrier to improvement in schools."

A West Sussex spokeswoman said: "We give schools funding for one teacher for every 27 pupils but it's down to the headteachers to allocate that funding. We offer advice and guidance but they might decide to use the money elsewhere."

She said teaching assistants helped ease pressure on teachers with large classes.

There is a legal requirement that children in Key Stage 1, aged four to six , cannot be in classes larger than 30 but there is no requirement for older children.

A Brighton and Hove City Council spokeswoman said: "The city's schools meet national requirements regarding class sizes for Key Stage 1, where there must be 30 or less per qualified teacher.

"At Key Stage 2 there are no minimum class size requirements, although locally we recommend no more than 32.

"We cannot however prevent the independent admissions appeals panels from admitting extra pupils.

"We monitor class sizes very closely and have provided additional financial support for extra teachers in Key Stage 1 where necessary."

An East Sussex County Council spokeswoman said steps had already been taken to reduce primary class sizes.

She said: "Last year we introduced a class size policy of 30 pupils per class, replacing the previous 35 pupils per class.

"Currently, nearly all pupils in reception and years one and two - around 43 per cent of all primary aged children - are in classes of 30 or less. Clearly this policy will take time to work through to all primary years."