The world's first genetically modified humans have been created, it was revealed last night.

The disclosure that 30 healthy babies were born after a series of experiments in the United States provoked another furious debate about ethics. So far, two of the babies have been tested and have been found to contain genes from three 'parents'.

Fifteen of the children were born in the past three years as a result of one experimental programme at the Institute for Reproductive Medicine and Science of St Barnabas in New Jersey. The babies were born to women who had problems conceiving. Extra genes from a female donor were inserted into their eggs before they were fertilised in an attempt to enable them to conceive.

Genetic fingerprint tests on two one-year- old children confirm that they have inherited DNA from three adults --two women and one man. The fact that the children have inherited the extra genes and incorporated them into their 'germline' means that they will, in turn, be able to pass them on to their own offspring.

Altering the human germline - in effect tinkering with the very make-up of our species - is a technique shunned by the vast majority of the world's scientists. Geneticists fear that one day this method could be used to create new races of humans with extra, desired characteristics such as strength or high intelligence.

John Smeaton, national director of the Society for the Protection of Unborn Children, said: 'One has tremendous sympathy for couples who suffer infertility problems. But this seems to be a further illustration of the fact that the whole process of in vitro fertilisation as a means of conceiving babies leads to babies being regarded as objects on a production line.