The Archbishop of Canterbury recently questioned the need, legality and morality of updating Britain's Trident nuclear deterrent.

On Monday, Tony Blair outlined plans to spend up to £20bn on a new generation of submarines for Trident missiles, telling MPs it would be "unwise and dangerous" to give up nuclear weapons.

But Archbishop Rowan Williams has determined that a national debate on Trident should take place and that the Church of England's voice should be heard.

He said many people would never accept the morality even of threatening destruction by "intrinsically indiscriminate" weapons.

In July, a group of bishops warned Mr Blair that the possession of Trident weapons was "evil" and "profoundly anti-God".

The head of the Roman Catholic Church in Scotland, Cardinal Keith O'Brien, said that rather than protecting peace, the system prevented it.

The leader of the Anglican Church in Wales, Archbishop Barry Morgan, insisted in September that the money spent on it could instead save 16,000 children from dying from preventable diseases every day.