The Conservatives warn of an 'uneducated underclass'

The document from the party's social justice policy group says only 17% of white male students gained five or more A*-C grade GCSEs.

That compares with 19% for boys of Caribbean origin, Tories suggest.

The government disputes the findings, saying it is working "to better engage boys in education".

The study, "State of the Nation - Educational Failure" was compiled by the Tories using statistics from the Department for Education and Skills (DfES) as part of the wide-ranging policy review set up by party leader David Cameron.

It compared the exam performance of boys in receipt of free school meals from different ethnic backgrounds.

It suggests that social issues, such as a lack of parental support, peer pressure and family breakdown are contributing to white working-class teenagers' poor exam results.

Culture not ethnicity or cash is the key to educational achievement. Iain Duncan Smith MP Conservative

But the report adds that black teenage boys are affected by similar factors, yet are performing marginally better at school.

The policy group's chairman, ex-Tory leader Iain Duncan Smith, said the issue had clear implications for policy making.

"The fact that poor children from Chinese and Indian backgrounds, where family structures are strong and learning is highly valued, outscore so dramatically children from homes where these values are often missing, suggests that culture not ethnicity or cash is the key to educational achievement."

The study goes on to argue that the problem cannot be tackled just by increasing state funding for education.

It claims that despite a 50% increase in spending on schools, "academic standards among the poorest pupils have scarcely risen at all".

We are delivering a curriculum and school experience to better engage boys in education. DfES spokesman

The DfES says it has a number of measures aimed at boys from all ethnic backgrounds, who have traditionally performed less well at school than girls.

A spokesman said: "Massive investment in personalised learning, as well as reforms to 14-19 education, will deliver catch-up classes, challenge for gifted and talented pupils, and a new curriculum to keep all pupils engaged and excelling in learning."