Almost a third of the school children in Sussex played truant last year.

One in three secondary pupils in East Sussex skipped classes without permission for at least one half-day, the Department for Education and Skills said.

In West Sussex, the figure was one in five.

The Government is trying to clamp down on truancy, whether caused by young people deliberately staying away or by their parents taking them out of school without permission.

Last year, of 27,467 children aged 11-16 in East Sussex, 10,363 took at least a half-day off without asking. The average number of days missed was five-and-a-half.

Pupils failed to attend 1.41 per cent of lessons without permission.

That is the same figure as in 2003-4 but it is still higher than the national average of 1.25 per cent.

In West Sussex, out of 42,398 secondary pupils, 9,289 missed an average of six-and-a-half days each.

The proportion of classes skipped was 0.93 per cent less than the national average but up from 0.73 per cent in 2003/4.

East Sussex County Council said it was working hard to combat truancy but needed the help of parents to succeed.

Principal education welfare officer Penny Lavan said: "If your child has two weeks off a year, every year, they are losing five per cent of their education. There has been research showing that children with poor attendance in Year 7 are likely to lose a grade at GCSE.

"If parents work with the schools there is a much greater chance of attendance improving."

Ms Lavan said the number of unauthorised absences in secondary schools may not have gone down but the proportion of lessons missed with the school's agreement had reduced from 6.49 to 5.85 per cent. This was, she said, because schools were getting tougher.

The local education authority works with the police to carry out "truancy sweeps" in town centres, approaching children who look as if they should be at school.

From the start of this month East Sussex County Council has had the power to charge parents £50 if their children do not turn up to school. Warning letters have already been sent out.

The authority has previously taken parents to court for allowing their children to skive.

West Sussex County Council has been using the scheme for some time and has fined 19 families.

In primary schools in East Sussex in 2004-5, 9,952 out of 32,708 pupils skipped one half-day or more without permission. They missed an average of four days each. In West Sussex, 5,546 out of 51,735 missed an average of six days.

The Government has announced its own plans to focus on the 146 schools in the country with the biggest truancy problems. It refused to say if any were in Sussex.