Desmond Tutu has become the latest high-profile figure to come out in favour of a change in the law on the right to die, days before a House of Lords debate on the issue.
The world-renowned religious leader, writing in the Observer newspaper, said he reveres "the sanctity of life - but not at any cost".
His comments come after the former Archbishop of Canterbury Lord Carey said he had changed his mind on the issue of assisted dying, after considering cases like that of locked-in syndrome sufferer Tony Nicklinson and "the reality of needless suffering".
On Friday former Labour Lord Chancellor Lord Falconer's Bill on assisted dying, which proposes allowing doctors to prescribe a lethal dose to terminally ill patients judged to have less than six months to live, will come before the House of Lords for a second reading.
Retired archbishop Mr Tutu, while recognising the sensitive nature of the subject, said there needs to be a greater focus on the treatment and preservation of newborns and the young.
"Money should be spent on those that are at the beginning or in full flow of their life. Of course, these are my personal opinions and not of my church," he wrote.
On a personal level the 82-year-old South African said he would not want his life "prolonged".
"Yes, I think a lot of people would be upset if I said I wanted assisted dying. I would say I wouldn't mind actually," he wrote.
Strongly condemning the treatment of Nelson Mandela in his later years, Mr Tutu said it was "an affront to Madiba's dignity" to force him to be part of a television appearance with other political leaders as he neared the end of his life.
He notes that the Lords Bill will be debated on the first anniversary of Mr Mandela's death.
Referring to South Africa, where assisted dying is also currently illegal, Mr Tutu said the country's "hard-won constitution that we are proud of...should provide a basis to guide changes to the legal status of end-of-life wishes to support the dignity of the dying."
Lord Falconer welcomed comments, telling the Observer: "I am really glad that someone of his stature is taking part in this important debate."