The British former ambassador to the UN during the last Gulf war has warned the government against seeking specific UN approval for war against Iraq.

Lord Hannay of Chiswick said to do that would be a "mistake" because there was "a danger" that other members of the UN Security Council could veto a second resolution and prevent it being passed, even if there was a case for it.

Tell us where this stuff is Hans Blix

The suggestion came after chief weapons inspector Hans Blix said Iraq's 12,000 page declaration on its weapons programmes gave him no "confidence that no weapons of mass destruction programmes remain".

He also accused the US and UK governments of not providing enough intelligence to help his team search for weapons of mass destruction in Iraq.

Colin Powell, the US Secretary of State, said Saddam Hussein's failure to provide a full declaration placed him in "material breach" of UN resolution 1441 on disarmament.

UK Foreign Secretary Jack Straw warned that Saddam must meet his obligations, stressing: "There has already been one trigger pulled. In a sense they now have their finger on the other trigger."

'No legal requirement'

The British government would prefer to obtain full international backing before going to war with Iraq through a second UN resolution.

Whitehall sources told The Times that US President George Bush would support this measure if it was likely the resolution would be approved.

The international community will not blink first, says Straw

But Crossbench peer Lord Hannay said the UK government needed to gauge the attitude of the other permanent members of the Security Council, and the evidence, before pressing ahead.

He argued that there was "no legal requirement" for a second resolution because Iraq would place itself "in jeopardy" if it breached resolution 1441 and therefore the ceasefire agreed in 1991.

He said other members of the Security Council could prevent a second resolution being passed for "political reasons ... irrespective of whether there's a case for it".

"But if you have a situation like we had back in 1999 over Kosovo where there was one permanent member, Russia, simply stated flatly that whatever the evidence of Milosevic�s misdeeds in Kosovo, they were not going to vote for the use of force, then I think it probably would be a mistake [to go for a second resolution].

"British ministers have said, and from my own personal experience I happen to agree with them, that there is no legal requirement for a second resolution," the peer told BBC Radio 4's Today programme.

"That Iraq, if it does not meet 1441 - the resolution that was passed last autumn - is in fact in breach of the cease fire provisions of the resolution of 1991, which brought an end to the Gulf war conditional on Iraq rendering harmless, destroying and revealing all its programmes.

The Ark Royal is sailing towards the Gulf next month

"If it is in breach of that, it is in breach of the ceasefire and therefore it is in jeopardy.

"But, it is probably more a matter of politics than it is of law whether governments go for a resolution or not and that remains to be decided.

Lord Hannay said it "seems pretty certain" that there are materials "being concealed" in Iraq.

'Show me the weapons'

Earlier, chief weapons inspector Dr Blix urged the US and UK to provide intelligence to help his team search for weapons of mass destruction in Iraq.

He said his inspectors were not receiving the support they needed from the western powers.

"If the UK and the US are convinced [that Iraq has weapons] and they say they have evidence, then one would expect that they would be able to tell us where this stuff is," he said.

Mr Straw promised that the international community would not "blink first" as Saddam Hussein might hope.

War was not inevitable unless and until the UN or its members decided military action was the only way to get Iraq to comply with its obligations, he said.

The aircraft carrier Ark Royal is to lead a naval taskforce sailing towards the Gulf next month, on their way to "long-planned" exercises in the Indian Ocean.