Chief Rabbi Ephraim Mirvis has joined other faith leaders in opposing a move to legalise assisted dying.
Rabbi Mirvis, the Archbishop of Canterbury Justin Welby, and 23 other prominent figures from the Christian, Muslim and Sikh communities expressed concern that possible new legislation would leave the elderly and terminally ill unprotected.
In a letter sent to every MP, the leaders called for a private members bill to be rejected when it is debated in the House of Commons next week, over fears that it could legitimise suicide.
Their concern was "rooted in a profoundly human and profoundly sacred calling to care for the the most vulnerable in our society".
The bill "has the potential to have a significant impact", putting many more at risk than it would help, they wrote.
Some "500,000 elderly people are abused each year, most by family members, often for financial reasons. Many of these would be vulnerable to pressure to end their lives prematurely".
The leaders said they believed "the best response to individuals' end-of-life concerns lies in ensuring that all receive compassionate, high-quality palliative care and that this is best pursued under current legislation".
The private members bill, put forward by Labour MP Rob Marris, would allow patients judged to have less than six months to live and who had expressed a clear intention to end their lives, to be allowed to do so.
Mr Marris said the letter helped to inform the debate.
Signatories to the letter, which was published in the Observer, included Cardinal Vincent Nichols, Catholic Archbishop of Westminster, Dr Shuja Shafi, secretary general of the Muslim Council of Britain and Lord Singh, director of the Network of Sikh Organisations UK.
Writing in the newspaper, the Archbishop of Canterbury said the bill crossed "a legal and ethical Rubicon".
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