The NHS has warned the need for organ donors has never been greater
Leaders of the UK's main religions have appealed to their followers to support a campaign to register as organ donors.
They are trying to counter uncertainty about what their religions teach about organ donation.
The Roman Catholic Archbishop of Westminster, the head of the Muslim Council of Britain and the Chief Rabbi are among those involved.
Three people die a day in the UK because there is no suitable organ available for transplant for them.
BBC News Religious Affairs Correspondent Robert Pigott says senior clergy report that some people are unsure what their religion teaches about the subject.
Act of generosity
The Church of England says organ donation is a Christian duty.
The leader of the Roman Catholic Church in England and Wales - the Archbishop of Westminster, the Most Reverend Vincent Nichols - described it as a true act of generosity.
The head of the UK Hindu Council, Anil Bhanot, said it was natural for Hindus to donate body parts, as well as goods, at the end of their lives.
There was a record number of organ transplants in the UK last year but attempts to increase the supply have had limited success.
There were 3,504 organ transplants between April 2008 and March 2009, up 8% on the previous 12 months.
But the NHS warned the need for donations had "never been greater", with 10,000 people awaiting a transplant and 7,000 blood donations needed each day.