Hundreds of medical professionals have told Health Secretary Sajid Javid they oppose plans for a new law on assisted dying and will refuse to help people take their own lives.

An open letter with 1,689 signatories, including current and retired doctors, nurses, pharmacists and medical students, said “the shift from preserving life to taking life is enormous and should not be minimised”.

The Assisted Dying Bill, which would allow terminally ill adults to legally seek assistance to end their lives, will have its second reading in the House of Lords on Friday.

If passed, it will enable adults who are of sound mind and have six months or less to live to be provided with life-ending medication with the approval of two doctors and a High Court judge.

Campaigners say it will give people with terminal illnesses greater choice and control over how and when they die, with safeguards in place to protect them and their loved ones.

Opponents say it will put pressure on people to end their lives and that current laws protect the vulnerable.

The letter reads: “The prohibition of killing is the safeguard. The current law is the protection for the vulnerable.

“Any change would threaten society’s ability to safeguard vulnerable patients from abuse, it would undermine the trust the public places in physicians, and it would send a clear message to our frail, elderly and disabled patients about the value that society places on them as people.”

The signatories conclude: “We would not take patients’ lives – even if they asked us to – but for the sake of us all, and for future generations, we ask that the law remains unchanged.”

It came as three faith leaders expressed their “profound disquiet” over the Bill.

Archbishop of Canterbury Justin Welby, Roman Catholic Cardinal Vincent Nichols and Chief Rabbi Ephraim Mirvis have written to Mr Javid warning him of “the ‘real-life’ practical inadequacies of the proposed safeguards”.

They note that, while the Bill seeks to alleviate suffering, they disagree on the “means advanced to address this very real concern”.

They wrote: “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.”

The campaign group Dignity In Dying said assisted dying is an issue “whose time has come”, and claimed the majority of public support a law change.

A survey last year by the British Medical Association found that 50% of doctors believe that there should be a change in the law to permit doctors to prescribe life-ending drugs, with 39% opposed and 11% undecided.

Members of the doctors’ union voted last month to adopt a neutral stance on assisted dying.

Tom Davies, Dignity in Dying’s director of campaigns and communications, said: “Under Baroness Meacher’s Assisted Dying Bill, doctors who oppose assisted dying will be under no obligation to participate, but they should not stand in the way of giving dying people choice over their deaths.

“The most important voices in this debate are the terminally ill people who, under the UK’s outdated ban on assisted dying, are denied choice the safe, legal choices they want, forced instead to suffer against their wishes, travel to Switzerland as 50 Britons do every year, or take their own lives at home.”

The Ministry of Justice said any law change “in an area of such sensitivity and importance” is for MPs rather than Government to decide.

– The Samaritans can be contacted on 116123 or email jo@samaritans.org