The BBC's Margaret Gilmore:"Thousands of pigs,poultry and some sheep and cattle are routinely given antibiotics"

The Advisory Committee on the Microbial Safety of Food says in its report that the risk is shown by the evidence.

It says that "shows conclusively that antibiotics given to animals result in the emergence of some resistant bacteria which can infect humans".

Infections which may become resistant to treatment include salmonella and E.coli.

It urges "a cautious approach to the use of antibiotics as growth promoters.

Chairman of the Advisory Committee, Douglas Georgala "The development of new antibiotics is becoming more and more difficult"

The committee calls for urgent action to reduce overuse, and for further research to establish how serious the problem is.

The British Medical Association (BMA), which supports efforts to reduce GP prescription of antibiotics to reduce the development of resistance to treatment, welcomed the report.

"We must all play our part in a multi-pronged attach on this problem of antibiotic resistance," said Dr Simon Fradd of the BMA.

The advisory committee's report comes as the Soil Association warns that the problem of antibiotic resistance could cause "a major epidemic of diseases".

It says the problem could eventually prove more costly than the BSE crisis.

No new classes of antibiotics

Spokesman Richard Young said the four major food poisoning bugs - salmonella, E.coli, campylobacter and enterococci - were directly linked to overuse of antibiotics in agriculture.

He believes further research would reveal a link between overuse and other health problems.

"Bacterial resistance has now developed in all classes of antibiotics and the real problem is that no new class has been developed in the last 20 years," he added.

The Soil Association claims a European Union ban on four growth promoters because of fears of antibiotic resistance has actually worsened the situation.

It says this is because farmers are substituting other potentially more harmful antibiotics for the four banned drugs.

Some bugs are developing resistance to antibiotics

These include avilamycin, which was previously little used in farming.

Mr Young said the drug was virtually identical to Ziracin, a "vitally important" new treatment being piloted in British hospitals.

It is being used to treat infections which have proved resistant to other drugs, such as MRSA and multiple drug-resistant strains of pneumonia and meningitis.

Methicillin-resistant Staphylococcus aureus or MRSA is becoming increasingly common in hospitals and community homes in the UK.

The Soil Association says avilamycin has been fed to every broiler chicken in the country and that they will soon be on sale.

More natural conditions

Helen Browning, chairman of the association, said: "Our continuing campaign against the overuse of antibiotics in intensively reared animals is not intended to prevent farmers treating genuine illness.

"Its purpose is in fact the very opposite - to ensure that in the future antibiotics continue to remain effective and retain their same ability to save lives and to prevent suffering in both people and animals."