CAMPAIGNERS are confident MSPs will reject plans to permit assisted suicide in Scotland when proposed legislation faces a crunch Holyrood vote on Wednesday.

Care Not Killing, an umbrella body for groups opposed to the controversial move, believes between two thirds and three quarters of MSPs will vote to block the Assisted Suicide Bill.

A comprehensive defeat for the Bill would place MSPs at odds with public opinion on the issue, according to the campaign's own polling.

However, Care Not Killing insists strong public support for allowing assisted suicide falls dramatically when details of how the legislation would operate in practice are explained to people.

MSPs will decide on Wednesday whether the Bill should move to its next parliamentary stage and face further scrutiny or be killed off.

Under the plans, originally brought forward by the later Margo MacDonald, patients with a terminal or life-shortening illness, could notify their GP of their wish to die.

After a series of checks, a "licensed facilitator" would be able to obtain a lethal prescription to enable the patient to end their life.

Care Not Killing claimed 65-75 per cent of MSPs were poised to vote against the legislation, based on their past public statements.

The group included First Minister Nicola Sturgeon in a list of 59 MSPs opposed to the Bill, after she said earlier this year she was "not convinced" by the move.

A further 17 MSPs are "minded" to vote against, the group said, with 30 either definitely in favour or inclined to support the legislation.

The group estimates 21 MSPs are undecided.

If the vote goes as Care Not Killing expects, MSPs will be on the wrong side of public opinion, according to a poll commissioned by the campaign.

The survey of 1004 adults by Orb International found 38 per cent of Scots said they agreed with the principle of assisted suicide and a further 35 per cent agreed strongly.

Eight per cent disagreed and a further seven per cent disagreed strongly, while 12 per cent were unsure.

However, 22 per cent of those questioned changed their minds when it was suggested to them that terminally ill patients might feel pressurised into ending their lives because their feared they had become a burden.

A similar number changed their view when it was put to them that that assisted suicide was no longer restricted to people with terminal illnesses in countries where it had been legalised.

Dr Gordon Macdonald, convenor of Care Not Killing, said: "We are extremely hopeful that the Bill will be comprehensively rejected by MSPs on Wednesday but we don't want to pre-judge anything and will await the decision of the MSPs.

"This has been a long, arduous and highly-charged campaign with powerful arguments being made.

"However, we have said along that assisted suicide is unnecessary, unethical and uncontrollable and that this Bill is flawed in principle."

Supporters of the Bill dismissed claims public support was unreliable.

Bob Scott, spokesman for My Life, My Death, My Choice, a group campaigning in favour of the Bill, said: "This poll is a desperate and misleading ploy by opponents who are set on denying those enduring terrible suffering the choice to end their life at a time and in a place and manner of their choosing."

He said other surveys have shown that when the arguments both for and against assisted suicide are presented, public support "remains around the same, at over 65 per cent".

He added: "Indeed, the most recent poll conducted in Scotland revealed that 75 per cent of Scottish voters not only support the legislation but feel it is important that this Bill becomes law.

"We are confident that when MSPs learn more about the strong public support the Bill actually has, they will vote in its favour at stage one to allow the debate to continue."