The House of Lords' leading expert on elderly care today calls for doctors to be allowed to help people end their lives.

Baroness Murphy, an adviser to the Chief Medical Officer and the World Health Organisation, is calling for the law to be changed so doctors can prescribe lethal drugs for terminally ill people who want to die.

'There is a broad proportion of people with terminal illnesses who know life is coming to an end, accept that, and want to make their own decisions about the time that they go,' said Murphy, who is also a vice-president of the Alzheimer's Society. 'For me, it's about recognising the autonomy of the individual.'

Her intervention in the emotive debate comes as the British Medical Association prepares to discuss the issue of euthanasia later this week.

Euthanasia involves a doctor actively ending a patient's life, and it is believed a growing proportion of the British Medical Association (BMA) is receptive to a law change similar to that envisaged by Murphy. This week four branches of the BMA will call for the organisation, which represents the interests of almost 130,000 doctors, to change its policy on so-called 'assisted dying'. The BMA is unlikely to change its position, but the fact it has been prepared to discuss euthanasia is seen in some quarters as a sign that attitudes are changing.

Last night pro-life groups reacted with dismay to Murphy's decision to speak out in favour of a law change. 'We're completely opposed to it. It would allow somebody in a terminally ill condition to be manipulated. She's doing an appalling disservice to the old,' said Phyllis Bowman, executive director of the group Right to Life.

In October parliament will debate a select committee report on proposals to allow assisted dying.