British babies fed on breast milk could be receiving as much as 40 times World Health Organisation (WHO) recommended levels of a wide range of potentially harmful chemicals, says a report.

The World Wide Fund for Nature (WWF) says more than 350 man-made pollutants have been identified in the breast milk of women in the UK.

These include 87 dioxins, the poison which sparked the recent Belgian health scare.

But experts have urged mothers to continue breast feeding, saying the potential benefits to the child still outweigh the risks posed by contaminated milk.

Cow's milk, the only alternative, could be equally contaminated, they add.

The report, "Chemical Trespass: A Toxic Legacy", was written by Gwynne Lyons, a scientific consultant on toxic materials for the WWF.

She said: "Sadly, we are only getting part of the picture. The full range of contaminants in UK breast milk is unknown, because past surveys have focused on a limited range of substances, many of which have been banned for several years."

Apart from the dioxins, which can build up in the body over time, and cause cancer, the report identifies about 190 other volatile chemicals, which include some industrial chemicals and pesticides.

UK babies are being exposed to between 10 and 40 times the WHO's daily limits for these so-called "gender bender" hormone-disrupting chemicals.

Birth defects and behavioural problems

The report says there is growing scientific evidence to show that some can cause birth defects, and reproductive, behavioural and developmental abnormalities in wildlife.

Bottle-feeding with cow's milk or formula may not avoid the problem

It fears that similar problems may emerge in humans, affecting children's mental development and increasing their risk of cancer.

However, Elizabeth Salter, the head of WWF-UK's toxics programme, said that women should not be discouraged from breast feeding.

She said: "It is the best option for new mothers and their babies. It provides immunological advantages, important nutrients, and encourages bonding.

"Reducing the exposure of the unborn and new-born infant to pollutants is now a major challenge for modern society."

Call for full survey of problem

The WWF is calling for an extensive survey of human contamination in the UK, and is calling for governments to eliminate the use and production of chemicals which are hard to break down.

The deputy general secretary of the Royal College of Midwives, Louise Silverton, has also called for an urgent response.

She said: "The issue of environmental pollutants is not simply one for breast milk but potentially affects all foods, including cow's milk from which many infant formulae are derived."