Mr Johnson wants more outreach workers in less privileged areas

The Labour deputy leadership contender said an extra �1bn would be spent on tackling this by 2011.

In a speech at the IPPR think tank, he said some schools were "routinely" discriminating against poor children, putting them in lower sets.

He wanted more literacy and numeracy projects and outreach workers.

The minister highlighted the fact that children who did not get free school meals - a standard deprivation measure - were twice as likely to get five good GCSEs as those who did.

"It is now harder to climb the social ladder in Britain than anywhere else in Europe," he said.

This would change only if the educational attainment gap were closed.

"The first step must be to resist the self-fulfilling culture of defeatism throughout children and families from poor backgrounds," he said.

"We know that kids from poorer backgrounds are routinely entered in lower streams, regardless of prior attainment, and can be discriminated against in their grade predictions."

Science project

Mr Johnson's speech on social mobility comes as the medical research charity, the Wellcome Trust, publishes details of a project in a disadvantaged area of London which saw pupils getting much better results in GCSE science.

The three-year scheme, funded by the trust, involved 31 pupils from three state schools in the London Borough of Barking and Dagenham and academics at the London School for Hygiene and Tropical Medicine (LSHTM).

After a week-long summer school, the scheme encouraged the pupils to undertake their own science and research projects, for example on asthma in the UK, malaria prevention and the impact of global warming on disease.

An initial analysis of their subsequent GSCE science studies results showed 73% of the pupils achieved at least one grade higher in GCSE science than would have been expected on the basis of their performance in national tests in year 9.

And 50% of this group achieved two grades higher than expected.

LSHTM senior lecturer Dr Carolyn Stephens said: "The feedback we have had from the young people is tremendous and we were surprised by the diversity and appeal of the public health topics they chose to work on.

"We had expected them to focus on public health topics relevant to their own daily lives in Britain," she said.