Supporters of the Care Not Killing Alliance include health workers and human rights groups.

Top target will be a Bill currently under consideration by peers that would legalise physician-assisted suicide.

The move follows the relaunch last week of the Voluntary Euthanasia Society, which is now known as Dignity in Dying.

Among the 18 groups who have joined the new alliance are the Association of Palliative Medicine, the British Council of Disabled People and the National Centre for Independent Living.

It is also backed by the crossbench peer Baroness Finlay of Llandaff, who sits on the All Party Parliamentary Group on Dying Well, and is an expert on palliative care.

The group said action was needed to counter the pro-euthanasia lobby, which it said was now making a determined attempt to change the law to allow doctors to "kill their patients".

Proposed legislation

The Bill which proposes the legalisation of physician-assisted suicide - where a doctor gives a patient the drugs needed to end their life - has been put forward by cross bench peer, and former human rights lawyer Lord Joffe.

Initially, it also proposed the legalisation of voluntary euthanasia, whereby a doctor could actively end a patient's life. But these plans were dropped after they received an unfavourable response in the Lords.

The debate made the headlines last week when retired doctor Anne Turner, who had a progressive debilitating disease, travelled with her family to Zurich to end her life at the controversial Dignitas clinic.

Dr Turner made her case public in an attempt to mobilise public opinion behind Lord Joffe's Bill.

John Wiles, of the Association of Palliative Medicine and a member of the Care Not Killing steering group, said: "There is an urgent both to campaign for more and better palliative care whilst opposing any change in the law.

"Currently opposition to proposed changes in the law on assisted dying is widespread - but fragmented.

"This coalition will bring together those many organisations and individuals, both in the healthcare sector and outside it, who regard euthanasia in any form as an unacceptable way forward."

Baroness Finlay said: "The UK has led the world in the provision of palliative care which strives for true dignity in dying. We need to promote better understanding of the process."

Meanwhile, Dignity in Dying representatives defended the new name of the organisation, arguing it would aid its efforts to campaign on all end of life medical treatment.

However, the Association of Palliative Medicine accused the organisation of trying to suggest dignity in terminal illness can only be won by euthanasia.

It has written to Trade and Industry Secretary to oppose the change.