The convenor of the Kirk's Church and Nation Committee, the Reverend Alan MacDonald, said that going to war when there are other options available would be foolhardy and immoral.

In his letter Mr MacDonald said that war should only be considered as a last resort, and only if express approval is given by the House of Commons.

A new and specific mandate from the UN will have to be given before military action is considered, he added.

Tony Blair will release a dossier on Iraq

The prime minister's official spokesman said on Monday that Iraqi leader Saddam Hussein must not be allowed to exploit diplomatic manoeuvring within the UN to block the demands to disarm.

On Tuesday, the UK Government will publish a 55-page dossier outlining the threat allegedly posed by the Iraqi leader's weapons programme.

Parliament will be recalled at 1100 BST on Tuesday to discuss the issue.

Mr Blair's spokesman said the dossier would "nail the lie that they (Iraq) have no weapons of mass destruction".

The moderator of the Church of Scotland wrote to Prime Minister Tony Blair in August and urged him to attempt to prevent war.

In a speech to the Kirk's annual Guild meeting, Reverend Dr Finlay Macdonald, asked the prime minister to advise restraint in Washington.

The moderator also said that British troops should not be committed to fight alongside any American force without a clear UN mandate and the support of a majority of MPs.

He said starting such a war was not an appropriate use of power.