A new campaign by disability rights activists to limit the right to die launches at Westminster on Thursday.
The campaign - called Not Dead Yet UK Resistance - will be asking MPs to sign a charter in support of its aims.
It says that disabled and terminally ill people should enjoy the same legal protection as everyone else.
Those in favour of assisted suicide argue that opposing assisted suicide will condemn terminally-ill people to suffer needlessly.
The Not Dead Yet UK's charter includes a commitment to oppose any changes to existing laws which state that assisting a patient to commit suicide is illegal.
We do not support assisted suicide where someone who is not terminally ill is helped to end their lives
Sarah Wootton, Dignity in Dying
Their charter also states that disabled and terminally-ill people should have access to the health and social care that they need.
Not Dead Yet UK's convenor, Baroness Campbell of Surbiton, says she fears that cuts in services across the UK will create additional problems for disabled people.
"There have been two attempts to weaken assisted dying legislation in the past four years, with further discussions taking place in the Scottish parliament now," she said.
"We face a bleak situation if calls for assisted suicide to be lawful are renewed whilst vital services are being withdrawn or denied."
Baroness Campbell points out that disabled people need help and support to live, not to die.
"We cannot allow others to speak for us - especially those who seek to offer us the choice of a premature death: it is not a choice, it is to abandon us."
The campaign's launch includes the release of a DVD which documents personal stories of disabled people arguing for the right to live.
The campaign group, Dignity in Dying, says it actually agrees with many of the aims of Not Dead Yet UK.
"We too are concerned about disabled people becoming vulnerable to coercion," said the organisation's chief executive, Sarah Wootton.
"That is why we campaign for a transparent and safeguarded assisted dying law which would allow assisted dying only for terminally ill, mentally competent adults."
Ms Wootton says the law for which her group is campaigning would apply only to disabled people who were terminally ill, mentally competent but suffering unbearably against their wishes.
"We do not support assisted suicide where someone who is not terminally ill is helped to end their life."
Dignity in Dying points out that there is no evidence, from countries where assisted suicide is lawful, to show that there is a negative impact on disabled people.
But the group says that the current situation - which forces people to travel abroad to die - causes unnecessary suffering and is unacceptable.