A study of patients with sore throats in South Wales, published in the British Medical Journal, showed that doctors often prescribed antibiotics because they felt patients did not want to be "fobbed off" with other treatments.

They also said it was quicker to prescribe the drugs than explain the negative effects of overusing antibiotics, which patients often did not understand.

However, they recognised that in the long-term they were increasing their work because patients would then expect to have to consult their GP for drugs the next time they had a sore throat.

Research has shown that antibiotics are of little use in treating sore throats, which are often caused by a virus.

The BMJ says research suggests up to 75% of antibiotic use is "of questionable therapeutic value".

Government guidelines, published this week, say they should not be prescribed for viral sore throats. It also recommended a national campaign to educate the public about antibiotics.

There are fears that overprescription of the drugs is leading to the rise of drug-resistant bacteria.

Expectations

The researchers said a third of patients expected to be given antibiotics when they attended the GP surgery, although they did not tell the doctor this.

All but one of those who expected to be given drugs had gone away with a prescription.

However, many just wanted information and reassurance from their doctor.

Most did not know of the link between drug-resistant bugs and antibiotic use.