...A real tragedy. And to think it was preventable. Had only the American people demanded truth and accountability from the fraudster Bush Administration. We will inherit the dues spawned by this disaster in Iraq for many years to come... And not just Americans and Britons and Iraqis and those of the greater Middle East - the whole of humanity will bear the brunt of this cruel and insidious Bush Administration plot to do wrong.
Asked by the BBC's Lyse Doucet whether the situation in Iraq could now be classified as a civil war, Mr Annan pointed to the level of "killing and bitterness" and the way forces in Iraq are now ranged against each other.
"A few years ago, when we had the strife in Lebanon and other places, we called that a civil war. This is much worse.
"We have a very worrisome situation in the broader Middle East," Mr Annan said, linking the ongoing conflicts in Iraq and Lebanon with the Israeli-Palestinian conflict and tensions over Iran.
He admitted that the failure to prevent the US-led invasion of Iraq in 2003 was a major blow to the UN, one from which the organisation is only beginning to recover.