Foetuses and newborn babies do not understand feelings of pain, according to research published today in the British Medical Journal.

Infants do not fully recognise pain until they are about four months old, when they "learn" it from the outside world, said a Glasgow University psychologist, Stuart Derbyshire

His paper was immediately condemned by anti-abortion organisations.

Dr Derbyshire said he knew his position was controversial as doctors largely agree that babies can feel pain from birth, and added that anaesthetics should still be used in operations on very small babies because they lead to better recovery rates.

The BMJ analysis is the latest in an ongoing debate about infant pain, fuelled by moral arguments about abortion and medical debates about the use of anaesthetics.

The US is considering introducing a law forcing doctors to tell women seeking an abortion that there is "substantial evidence" it would cause an unborn child pain. The law would also state that a foetus older than 22 weeks be given painkillers before an abortion.

Dr Derbyshire said: "We need to remove this argument from the abortion debate. If you agree that foetuses feel pain that doesn't mean abortion is wrong; equally if I'm right and foetuses don't feel pain, that doesn't mean abortion is right."

But Phyllis Bowman of the group Right to Life called the research "rubbish", adding: "The foetus has the neurological structure before 10 weeks to feel pain."