The gender gap in GCSE performance is widening in England's poorest areas but boys living in more affluent parts are beginning to catch up with the girls in their class, official figures reveal.
The difference between the proportions of of girls and boys gaining five or more good GCSEs has doubled since 1997 in the country's most deprived wards.
By contrast, the proportion of boys reaching this benchmark in the richest 10 per cent of wards has risen slightly faster than that of girls since Labour came to power.
Public concern about the underperformance of boys has risen since the early 1990s as girls outstripped their male classmates.
The issue will again come under the spotlight during the next two weeks as this year's A-level and GCSE results are published.
Experts, politicians and pressure groups have put forward different explanations for girls' success such as the increase in coursework, boys'
laziness and claim that modern teaching is more female-friendly.
Labour came to power promising to boost boys' results but although the proportion getting five Cs or better has increased from 38 per cent in 1996 to 46 per cent last year, the gender gap has remained steady at 10 points.
The figures are revealed by David Miliband, school standards minister, in a parliamentary answer to Phil Willis, Liberal Democrat education spokesman.
Both boys and girls in deprived areas get much lower grades than their more advantaged peers.
But while girls in poor areas are improving faster than those in affluent areas, the gap between rich and poor boys has remained constant.
The percentage of girls in the most deprived areas getting five Cs or better has increased by 12 points since 1997 to 42 per cent while boys'
scores increased from 24 to 32 per cent.
In well-to-do areas the proportion of boys getting five good GCSEs increased from 52 to 60 per cent, compared to a rise from 64 to 71 per cent for girls.
Dr Deborah Wilson, Bristol university expert on the gender gap in schools, said that the differences are likely to be a result of factors outside school.
"The effect of poverty on exam results is greater than the effect of gender," she said.
"If we focus more on the reasons for poverty affecting performance we might get better results for both boys and girls."
Martin Ward, Secondary Heads Association deputy general secretary, said the improvement among girls in deprived areas was welcome.
However, he added: "The fact that boys are falling behind does raise extra worries. It is young men in these areas that often cause social problems.
They feel they cannot do well at school. Achievement is for boys in leafy areas down the road or even for girls at their school.
"Schools are trying to raise their self-esteem, but it is a problem for society as a whole."