The number of pupils who have left school without a single 'good' pass at GCSE under Labour will exceed two million within a year, according to figures obtained by the Tories.

The statistics show that rising numbers of top grades conceal widespread underachievement.

Experts believe teenagers will pass more than one in five exams at grades A* or A for the first time this year.

Failed: 2m students will leave school without a decent GCSE grade

However, the increase will be largely driven by grammar and independent schools.

At the same time, tens of thousands of teenagers are finishing school with little to show for 11 years of compulsory education.

Between 1998 - the year after Labour came to power - and 2007, 1.75million children left school without a single C grade in any subject.

The figure is expected to rise to 1.9million when this year's results are released on Wednesday, and on current trends it will pass two million by 2009.

The numbers leaving school without even being entered for a GCSE over the last decade will top 300,000.

The Tories, who obtained the figures through Commons written answers, said an 'entire generation' has been let down.

Families spokesman Maria Miller said: 'Eleven years after Labour came to power, almost two million children have left school without any "good" GCSE passes. The Government has let down an entire generation of pupils who are not getting anything like the basic set of qualifications they need to continue studying or get the job they want.'

Schools Minister Lord Adonis defended the results and told the Conservatives to 'stop peddling doom and gloom

But schools minister Lord Adonis said: 'At GCSE the gap in achievement between children from poorer and more affluent backgrounds is narrowing and results for children on free school meals are rising faster than the average.

'Rather than peddling doom and gloom on the day before thousands of young people receive their results, we suggest that the Conservatives get behind young people and celebrate their achievements.'

The figures came as separate research found a 'postcode lottery' among the GCSE results of the poorest children.

In Nottinghamshire, just 22 per cent of children on free school meals achieved five GCSEs at grades A* to C, according to figures compiled by the campaign group End Child Poverty. In Kensington and Chelsea, however, 59 per cent of the poorest students gained good grades.

London emerged as the best region for poorer children to go to school, with the East Midlands the worst.

Jason Strelitz, UK poverty spokesman for Save the Children, said: 'This shows there is no excuse for failing the poorest students.

'In areas like London, where national government has invested in improving education for the poorest, they have succeeded.'