Suicides involving over-the-counter painkillers have decreased since retail laws were tightened, according to Oxford research.

Prof Keith Hawton, of the Centre for Suicide Research, at Oxford University's psychiatry department, said fewer people had taken fatal overdoses of paracetamol and aspirin since shops were banned from selling more than 32 pills at a time.

New packaging legislation, introduced in 1998, means customers can buy no more than 32 tablets from pharmacists and a maximum of 16 in supermarkets and other stores.

Prof Hawton, based at the Warneford Hospital, found paracetamol suicides decreased by 21 per cent and aspirin deaths reduced by 48 per cent just 12 months after the legislation was introduced.

His research, published in the British Medical Journal, also found that liver failure from paracetamol poisoning decreased by 30 per cent, compared with 1996.

Prof Hawton said the legislation had been relatively successful in cutting 'impulse suicides'.

He believed that reducing pharmacy sales to a maximum of 16 tablets per shopper could help reduce suicide rates even further.