The debate over whether breast-feeding protects children against obesity in later life intensified yesterday as child health experts said that the latest research had established a strong link.

Unicef UK's Baby Friendly conference in Bournemouth will hear researchers say babies who are breast-fed are protected against high blood pressure and cholesterol.

But research published in the British Medical Journal last month, involving more than 5,000 children, found there was little evidence that breast-feeding protected youngsters against obesity.

Baby Friendly director Andrew Radford also called on the government to honour its pledge to ban all advertising of bottle feeding and formula milk in order to encourage more breast- feeding.

Child nutritionist John Reilly, of the University of Glasgow, will tell the conference that research shows breast-fed babies are at lower risk of obesity in later life.

Unicef said the government had not implemented an international code banning the promotion of bottle feeding, and so companies could use loopholes to promote products such as bottles and teats.

Mr Radford said: "If the government is considering banning advertisements for junk food for kids, it should first think about honouring its international obligation to support breast-feeding by banning all bottle-feeding promotion."

Research in the BMJ, carried out in Brazil and London, failed to find support for the claim breast-feeding reduced the risk of obesity. It said that in the US and Britain the incidence of breast-feeding had increased since 1990, but so had obesity.