Boys are not innately better at maths than girls, and any difference in test scores is due to nurture rather than nature, researchers suggested today.

According to new research published in the journal Science, the "gender gap" in maths, long perceived to exist between girls and boys, disappears in societies that treat both sexes equally. When girls have equal access to education and other opportunities they do just as well as boys in maths tests.

The research, led by Prof Paola Sapienza of Northwestern University in the US, investigated whether a global gender gap exists and whether it was the result of social engineering rather than intrinsic aptitude for the subject.

"The so-called gender gap in math skills seems to be at least partially correlated to environmental factors," Sapienza said. "The gap doesn't exist in countries in which men and women have access to similar resources and opportunities."

Researchers analysed data from more than 276,000 children in 40 countries who took the 2003 Organisation for Economic Cooperation and Development Programme for International Student Assessment (Pisa) - the internationally standardised test of maths, reading, science and problem-solving ability.

Globally, boys tend to outperform girls in maths (on average girls score 10.5 points lower than boys) but in more "gender equal societies" such as Iceland, Sweden and Norway, girls scored as well as boys or better.

For example, the maths gender gap almost disappeared in Sweden, while in Turkey girls scored 23 points below boys in maths.

Average girls' scores improved as equality improved and the number of girls reaching the highest levels of performance also increased, the researchers found. In Britain, girls fared only slightly less well than male classmates, with female pupils scoring an average of 0.7% less.

The research also found a striking gender gap in reading skills. In every country girls perform better than boys in reading but in countries that treat both sexes equally, girls do even better.

On average, girls have reading scores that are 32.7 points higher than those of boys (6.6% higher than the mean average score for boys). In Turkey, this amounts to 25.1 points higher, and in Iceland, girls score 61.0 points higher.

Sapienza said: "Our research indicates that in more gender equal societies, girls will gain an absolute advantage relative to boys."