Tony Blair faced demands for a full public statement last night as the first documentary evidence emerged about his attorney general's doubts about the legality of the Iraq war just 10 days before the Allied invasion.
Channel 4 News broadcast details of what it claimed was attorney general Lord Goldsmith's secret legal opinion to the prime minister of March 7th, 2003.
In it, Lord Goldsmith warned Mr Blair the British government would "need to consider urgently" the strength of its legal case if it failed to secure a second United Nations resolution sanctioning the military conflict.
And the programme said the contents of the document - which the government has refused to publish - differed sharply from the summary of the attorney's opinion presented to cabinet 10 days later when Lord Goldsmith advised that the military action was in fact lawful.
In the extracts published last night, Lord Goldsmith is said to have told Mr Blair the language of Resolution 1441 demanding Iraqi disarmament had left "the position unclear" and that it would be for the UN Security Council itself to decide whether Iraq was in breach.
The document warned that British troops involved in any invasion could face prosecution in the international courts and argued the "safest legal course" would be to secure a second UN resolution authorising war.
However, the document goes on to say that that argument would only be sustainable "if there are strong factual grounds for concluding that Iraq failed to take the final opportunity" to comply.
Lord Goldsmith said in a statement last night the document broadcast by Channel 4 "stands up the case that the Government has been making all along".