US Secretary of State Colin Powell has said Washington had a sovereign right to attack Iraq for failing to account for weapons of mass destruction, amid a growing rift with its European allies.
He also accused Saddam of having clear links to Osama bin Laden's al-Qaeda terror network, without offering evidence.
President Bush's Chief of Staff, Andrew Card, also warned the United States had not ruled out the use of nuclear weapons if Saddam deploys weapons of mass destruction against the United States and its allies.
Earlier, the UN nuclear watchdog agency said it will be informing the UN Security Council that it has yet to find any proof of Iraq's alleged secret atomic weapons programme.
The International Atomic Energy Agency chief Mohamed ElBaradei and chief UN weapons inspector Hans Blix will report to the council tomorrow.
UN search continues
UN arms experts meanwhile continued their search for illegal arms in Iraq on the eve of their crucial compliance report to the Security Council.
The United Nations and the Iraqi information ministry announced in separate statements that inspectors checked a total of 10 sites in Baghdad and other Iraqi provinces.
Among the inspection sites were a bovine plague control centre and a tuberculosis research facility in Baghdad as well as the university in the northern city of Mosul and an oil refinery in Biji, north of the capital.
Earlier, Former UN official Denis Halliday warned that the United States and Britain were ready to 'annihilate' Iraqi society in order to control the country's oil wealth.
The Irishman said that since the 11 September terrorist attacks, control of Iraq's oil had become essential for the survival of American economic superiority.
Mr Halliday was based in Baghdad between 1997 and 1998 when he resigned in protest at continued UN sanctions against Iraq.
