A Nazi-like plot to make genetically superior people is behind much of the sex education material in schools, a family rights charity has suggested.
The bizarre claim is made in a booklet by Valerie Riches, founder president of the charity Family and Youth Concern.
Mrs Riches has lectured around the world on sex education and is regularly quoted by national newspapers on the subject.
This week the Daily Mail, the Mirror, and the Daily Express carried comments from her criticising the Government's strategy for tackling teenage pregancies.
Her new booklet, Sex education or indocrination?, accuses the Family Planning Association of being at the centre of a group of organisations with a hidden agenda which includes the promotion of eugenics, the attempt to create "purer" races by only allowing selected people to breed.
She claims that the family planning movement was created because would-be eugenicists were forced to "go underground" after the fall of the Nazis.
Among those accused of being racists and eugenicists are Dr Marie Stopes, founder of the clinic which evolved into the Family Planning Association, and Margaret Sanger, founder of the international umbrella charity which contains the FPA.
Mrs Riches said the FPA and other organisations in its "network" continue to have a sinister influence over schools and officials in the Government, who she said had helped promote its agenda.
"Lying darkly beneath the persuasive contraceptive propaganda fed to children is a sinister attitude towards birth," she wrote.
"The instigators need to be identified and exposed, because they function with impunity, in secrecy or behind a screen of pseudo-respectability afforded by government funding for their activities and policies.
"It has never really been about education. Sex education bears the same relation to education as voodoo bears to medicine."
Mrs Riches, a former social worker, founded Family and Youth Concern (formerly the Family Education Trust) after becoming concerned about the education her children were receiving.
She told The TES she had been disturbed to learn about the conspiracy several years ago and had first feared she was "going bananas". She argues that schools should be wary of the advice from groups such as the FPA and should consider promoting abstinence instead.
The FPA dismissed the report as "totally unfounded". A spokeswoman said:
"We firmly believe in giving everyone the chance to make an informed choice about their sex lives."
The booklet's launch coincided with the publication of government figures which suggest that pregnancies among girls under 18 rose by 0.7 per cent in 2002.
Teenage pregnancy rates in the UK are the highest in western Europe, although they fell between 1998 and 2001.
Sex Education or Indoctrination? can be ordered at www.famyouth.org.uk