Many children are failing to go on to further education or a job

Dropping out of school and employment is a "striking and worrying" reflection on the education system's failure to cater for all children, David Bell added.

He told the New Statesman that "no one should be comfortable with an education system that results in so many children dropping out".

The education watchdog Ofsted is due to publish a report on the attainment of 14 to 16 year olds in England next week.

'Not cracking it'

Meanwhile, the government has promised to make lessons more interesting by fostering closer links between schools, colleges and the world of work.

It is also committed to expanding allowances worth up to �30 a week for the children of the poorest families to stay in school or job-related training, to cover the whole of England.

"We are not cracking it with these youngsters. As long as that remains the case, none of us can pack up our bags and go home," Mr Bell said.

"At 16, you are looking at one in five that we know really don't go anywhere at the end of compulsory schooling - neither to further schooling nor education nor, in many cases, to work."

In the end, we are all going to suffer if youngsters don't believe they can take part in society David Bell, chief inspector of schools in England

But Mr said Bell the fate of the missing 20% was "not a particularly hot political potato".

"That's the reality. It's tempting to say these young people and their families have disenfranchised themselves, that they're not as important as electoral target groups," he added.

"But I come back to natural justice and to social consequences. No one should be comfortable with an education system that results in so many children dropping out because that is in no one's interests.

"In the end, we are all going to suffer if youngsters don't believe they can take part in society, feel disenfranchised and turn to crime.

"I don't want to let this issue go quiet. There's a temptation to say how well we are doing and take the credit.