And Hans Blix, the former chief UN weapons inspector, said the US has failed to produce any evidence to prove Iraq posed a great enough threat to justify war.
Dr Blix said the coalition had not proved there was a 'manifest and imminent' threat from Saddam Hussein's regime.
And he maintained that military action went against the UN charter and that UN criteria for action had not been met.
'One is that there should be a manifest threat,' he told the BBC.
'The intelligence was not so strong in reality that it could be said to be manifest.
'And the second one would be the imminence of it. If they can develop weapons of mass destruction in five years or 10 years, well, that certainly is not imminent. So I think it probably failed, in my view, on these two accounts.'
Dr Blix said the UN charter allowed action in self-defence against an attack.
'It is contended now that in the day and age of biological weapons and weapons of mass destruction, one must interpret this more liberally, and that one cannot just sit and wait for them to develop their weapons fully and then attack.
'All right, if one begins to discuss that, I think one will have to put up new criteria: when would pre-emptive action really be permissible?'