"Sometimes the only chance of peace is readiness for war", Tony Blair has told a sceptical Labour conference.

Taking anti-war rebels to task, the Labour leader said that a UN mandate to tackle Saddam Hussein was necessary - but might not be sufficient.

"I know the worry over Iraq," he said. "People accept Saddam is bad. But they fear it is being done for the wrong motives. They fear us acting alone.

"So the United Nations route. Let us lay down the ultimatum. Let Saddam comply with the will of the UN."

"So far most of you are with me," Blair said referring to Monday's narrowly averted conference rebellion on the government's Iraq policy.

Blair told the conference that if the move to a UN solution was not backed by force then declarations of internationalism were self-defeating.

What if Saddam defies the UN, Blair asked? "If at this moment having found the collective will to recognise the danger, we lose our collective will to cat, then we will destroy not the authority of America or Britain but of the United Nations itself," he said.

Sometimes. the only chance of peace is a readiness for war."

Playing to the conference gallery, Blair argued that UN resolutions should apply to all - Baghdad and Israel.

"I agree UN resolutions should apply [to the Middle East] as much as to Iraq," he said to applause.