A law allowing doctors and relatives to assist terminally ill people to end their lives moved a step closer after the publication today of a Lords report.

The Lord's special select committee, set up last year to scrutinise Lord Joffe's patient (assisted dying) bill, urged the next parliament to debate the issue at "an early opportunity".

The bill passed through the parliamentary scrutiny procedures relatively unscathed and could now be set for further serious consideration after the expected general election.

The committee was aware that the bill will be a casualty of the expected dissolution of parliament later this week. Introduced last year, it proposes making assisted dying lawful for people with a terminal illness who are undergoing "unbearable" suffering and are competent to make their own decision.

A parliamentary joint committee on human rights had approved the bill on the grounds that it protects the interests and rights of vulnerable patients. The criteria also stipulated that the individual would have to be over 18 and should be a resident in England and Wales for not less than 12 months, to protect any proposed new legislation from attracting "health tourists" from other countries.

Today's publication tweaks some aspects of the bill, which had reached its second reading in the House of Lords. Under the select committee recommendations, a clear distinction should be drawn between assisted suicide and voluntary euthanasia to reach a view on whether a future bill should be limited "to one or the other or both".

Assisted suicide is where someone helps an individual end their life because they are no longer physically capable of doing it on their own, whereas voluntary euthanasia requires a doctor to administer the lethal dose.

The panel of peers also proposed replacing the criteria for allowing people to die which the bill defines as "unbearable" suffering, with "unrelievable" or "intractable" suffering or distress.

Doctors would also require a detailed explanation of the actions they would be able to take in providing assistance to suicide or in administering voluntary euthanasia. A conscience clause would protect medical practitioners who were opposed to implementing the new law.

In light of those also suffering from a psychological or psychiatric disorder, the report also calls for a definition of mental competence to be specified.

The select committee toured the US state of Oregon, the Netherlands, and Switzerland, where legislation is in place, to look at the different models that already exist. The report supersedes a previous parliamentary report published 10 years ago by the Lords medical ethics committee which rejected proposals to introduce legislation on assisted dying.

The issue attracted significant interest last year following the case of motor neurone disease sufferer Diane Pretty, who was denied the right to seek help from her husband to end her life.

The Voluntary Euthanasia Society described today's report as "very powerful". "It is a huge step forward and it brings the possibility of changing the law in this country forward by many years," said spokesman Mark Slattery.

Select committee chairman Lord Mackay of Clashfern said a wide range of views had been taken on board before compiling the report, which he said was premised on the principle of "patient autonomy".

"The message is the need to recognise that assisted dying and voluntary euthanasia can be regarded as simply alternative ways of legally ending a terminally ill patient's life," he said.

Debbie Purdy, who has suffered from chronic progressive multiple sclerosis for the past 10 years, welcomed the bill. Ms Purdy said making assisted dying lawful would help her live her life to the full until the last possible moment.

The issue is likely to split parliamentary opinion, however, and is likely to prompt heated debate within the pro-life lobby. Even Lord Mackay himself, current patron of the Lawyers Christian Fellowship, refused to confirm whether he was for or against the report's findings.

Opinion is also split in the medical profession with both the British Medical Association and the Royal College of Nursing opposed, while the Royal College of General Practitioners and the Royal College of Physicians take neutral stances.