The findings were released at a conference yesterday for more than 100 secondary schools which have been awarded Government-funded grants by the agency to improve standards of literacy and numeracy.
The survey of about 4,500 pupils and 186 teachers in 192 schools showed that one in six children found reading-course books hard and had problems using a dictionary. One in 10 believed they were fairly or very poor at reading for their age with the same percentage feeling the same about writing.
But they were less confident about writing than reading and even less happy about maths. A fifth said they needed extra help with reading and 39 per cent with writing, while almost 40 per cent said they needed extra help with maths. More girls than boys - 11 per cent compared with 8 per cent - thought they were poor at maths.
The BSA points out that this is survey of opinion. Pupils' ability was not assessed or tested. "Two pupils with exactly the same level of attainment may judge themselves differently."
The agency was reassured that more than a quarter of the teachers in the sample were aware of the BSA as it was asked by the Government to cover schools only a year ago. However, only a third of teachers had received in-service training on teaching reading and writing.
"This is hardly surprising. The vast majority of pupils are expected to have mastered basic skills by the time they go to secondary schools," comments the report.
But Alan Wells, director of the BSA, said he was concerned about anecdotal evidence that an increasing number of Year 7 pupils had reading ages more than two years behind their chronological age.
"This concerns us all. The survey indicates that pupils themselves recognise that they may need extra help."
What pupils and teachers in secondary schools think about basic skills, free from the BSA, Commonwealth House, 1-19 New Oxford Street, London WC1A 1NU.