Abortion of female foetuses to prevent the birth of daughters and ensure that families have sons is widely practised in Britain's ethnic communities, claims an investigation by the Independent.
Terminations based on sex have led to the "disappearance" of between 1,400 and 4,700 females from the national census records of England and Wales, the newspaper reported.
According to an investigation by the newspaper the practice is so widespread that it has tipped the natural 50-50 ratio balance of boys to girls within some immigrant groups.
Abortions on the grounds of gender are illegal in Britain. But an analysis of data from the 2011 national census - broken down by country of birth of both father and mother - revealed anomalies in the ratios of children's sexes in some immigrant families which The Independent said can only be easily explained by the abortion of female foetuses, with the hope of then quickly becoming pregnant with a boy.
A study of data from the Office for National Statistics commissioned by the newspaper revealed that in two-child families of some first-generation immigrants, having elder daughters significantly increased the chances of the second child being male.
The sex ratio of having a boy as the second child was heavily biased in families with mothers born in Pakistan and Afghanistan, with some evidence of similar for mothers from Bangladesh.
Such an imbalance in the sex ratio should not occur naturally, The Independent said.
Experts said there were two possible explanations - gender-based abortion, or women continuing to have children until the birth of a son.
Dr Christoforos Anagnostopoulos, a lecturer in statistics from Imperial College London, said: "The only readily available explanation that is consistent with a statistically significant gender shift of the sort observed in the census data is gender-selective abortion.
"In the absence of a better theory, these findings can be interpreted as evidence that gender-selective abortion is taking place."
Amartya Sen, an Indian-born economist and Nobel laureate who spoke out about millions of "missing women" in the world 25 years ago, said gender-based terminations were a new form of sex discrimination.
He told the Independent: "Selective abortion of female foetuses - what can be called 'natality discrimination' - is a kind of hi-tech manifestation of preference for boys."