One of Prime Minster Tony Blair's closest allies has implicitly criticised the British premier's tactics in the lead to to the attack on Iraq.
Mr Peter Mandelson told a centre-left conference in Hungary this evening that a second UN vote would have reduced the intensity of the rebellion against occupation forces in Iraq.
Mr Mandelson, once Mr Blair's top cabinet ally, said an intervention approved and led by the UN would have given the invasion more international legitimacy.
"Who can doubt that the insurgency in Iraq would today be a lesser problem if there had been a second resolution," Mr Mandelson told Budapest conference which comes ahead of a meeting of left-wing prime ministers.
The comments implicitly criticise the decision by the US and Britain to withdraw a draft resolution before the invasion in March last year after it was clear there were not enough votes.
France, Russia, Germany and China wanted more time for UN weapons inspections.
Washington and London still insist the war was still legally justified on the basis of a previous Security Council resolution, passed unanimously in November 2002.
But UN Secretary-General Kofi Annan said last month the invasion was illegal as it violated the UN charter. US President George W Bush and Mr Blair justified the invasion of Iraq by saying Saddam Hussein had weapons of mass destruction and links with al Qaeda. Both assertion have since been proven false.
Mr Mandelson, who will soon take his position as European Commission trade commissioner. said despite the deep divides left by the war, the left would re-unite and leaders must be prepared to take pre-emptive military action again.
"We live in a world of such tremendous potential dangers, we always have to manage risks. We cannot possibly abandon all possibility of pre-emption," he said.
Mr Blair will attend the summit tomorrow, and will also meet prime ministers in the Hungarian countryside on Friday.