British Foreign Minister Jack Straw said the US Secretary of State Mr Colin Powell made a "most powerful" case against Iraq.
Saddam is "gambling that we will lose our nerve rather than enforce our will," Mr Straw said.
He effectively set a deadline of February 14th for Saddam Hussein to prove he is complying with United Nations weapons inspectors or face military action.
Mr Straw told the Security Council: "This council will have further reports from the inspectors on Friday week. If non-co-operation continues, this council must meet its responsibilities."
"Our world faces many threats, from poverty and disease to civil war and terrorism. Working through this great institution, we have the capacity to tackle these challenges together. But if we are to do so then the decisions we take must have a force beyond mere words."
Mr Straw described Mr Powell's presentation as "a most powerful and authoritative case against the Iraqi regime".
He said the UN had given Saddam "a final opportunity to rid itself of weapons of mass terror" including gases, viruses like anthrax and smallpox and of the means to make nuclear weapons.
"Sadly the inspectors' reports last week and Secretary Powell's presentation today can leave us under no illusions about Saddam Hussein's response," he went on.
"Saddam Hussein holds UNSCR (the resolution) 1441 in the same contempt as all previous resolutions in respect of Iraq.
"Let us reflect on what that means - that Saddam is defying every one of us, every nation here represented. He questions our resolve and is gambling that we will lose our nerve rather than enforce our will."
AP