They said genetically modified dairy products from herds of similar cows could be sold in supermarkets and the research has the backing of a big biotechnology company.

British scientists said it had the potential to be of huge benefit, but the work is likely to inflame opposition to genetically modified foods.

Critics of the technology and animal welfare groups reacted angrily to the research, questioning the safety of milk from genetically modified animals and its effect on the cattle's health.

Professor Ning Li, the scientist who led the research and the director of the State Key Laboratory for AgroBiotechnology at the China Agricultural University, insisted that the genetically modified milk would be as safe to drink as milk from ordinary cows.

''The milk tastes stronger than normal milk,'' he said. ''Within 10 years, people will be able to pick up these products at the supermarket.''