Faith leaders have come together to oppose the legalisation of assisted suicide ahead of a debate in Parliament.

The Archbishop of Canterbury, the Chief Rabbi and the head of the Roman Catholic Church in England and Wales have expressed grave concerns about the risk to vulnerable people if assisted suicide is legalised.

The warning comes ahead of the second reading of Baroness Meacher's Assisted Dying Bill in the House of Lords on Friday.

The Bill proposes allowing terminally ill people with less than six months to end their lives by assisted suicide. 

In a joint letter to peers, Archbishop Justin Welby, Cardinal Vincent Nichols and Chief Rabbi, Ephraim Mirvis, called for the focus to be on "assisted living" rather than assisted dying.

They cast doubt on the adequacy of promised safeguards as they warned that the common good would not be served by placing the vulnerable in ever more vulnerable positions. 

Sharing their "profound disquiet" over the proposals, they instead called for a compassionate society that offers high-quality palliative care for people in the final months of life.

"By the faiths we profess, we hold every human life to be a precious gift of the Creator, to be upheld and protected," they say.

"All people of faith, and those of none, can share our concern that the common good is not served by policies or actions that would place very many vulnerable people in more vulnerable positions.

"We appeal to people of whatever faith or belief to join us through our common bond of humanity in caring for the most vulnerable people within our society.

"In contrast to the proposals in this Bill, we continue to call for measures to make high-quality palliative care available to all at the end of their lives.

"We believe that the aim of a compassionate society should be assisted living rather than an acceptance of assisted suicide."