"Our case is simply this. Not that we take military action come what may. But that the case for ensuring Iraqi disarmament is overwhelming," Blair said. "Alongside the diplomacy there must be genuine preparedness and planning to take action if diplomacy fails."
In a preface to the long-awaited 50-page dossier, Blair said that "Saddam Hussein is continuing to develop WMD (weapons of mass destruction), and with them the ability to inflict real damage upon the region, and the stability of the world".
"His military planning allows for some of the WMD to be ready within 45 minutes of an order to use them."
Iraq's foreign minister rejected the allegation.
"(Blair) said that he would announce evidence, but this is just scaremongering, exaggeration and lies," Naji Sabri told reporters in Cairo.
Iraqi presidential adviser Amir al-Saadi urged Blair to hand over the dossier to UN weapons inspectors for verification.
Iraq says it has no weapons of mass destruction. After Baghdad's defeat in the 1991 Gulf War, UN inspectors spent seven years in Iraq seeking out and destroying weapon stocks, but the United States and Britain say they did not find them all and that Iraq has now acquired new ones.
Blair's document said Iraq had tried to acquire "significant quantities of uranium" from Africa, despite having no nuclear power programme to justify it. But the premier told parliament he did not know whether the uranium had in fact been acquired.
"Intelligence shows that the present Iraqi programme is almost certainly seeking an indigenous ability to enrich uranium to the level needed for a nuclear weapon," the dossier said.
If existing UN sanctions remained effective, Iraq would be unable to produce nuclear weapons, it said. But if it obtained fissile material and other essential components from abroad, it could produce them in between one and two years.
The dossier also said Iraq had illegally retained up to 20 al-Hussein missiles with a range of 650km, capable of carrying chemical or biological warheads.
White House spokesman Ari Fleischer called the dossier "frightening" and hailed Blair's "very bold" speech.
But the editor of defence journal Jane's World Armies, Major Charles Heyman, said the dossier broke no new ground.
"There really is nothing new in it. Nothing that I haven't seen or heard of before. We were all expecting the evidence for war and what we got was evidence for UN inspections," he said.
"There is no smoking gun," said Iraqi-born analyst Mustafa Alani, now based in London.
But John Chipman, director of the International Institute for Strategic Studies, said it showed clearly that weapons of mass destruction were "very much at the heart" of Saddam's military planning.
Britain's Stop the War Coalition called the document "a shockingly flimsy pretext for mass-murder".
As the parliament debate got under way, protesters circled the building in an open-topped campaign bus, singing Give Peace a Chance.
In a bid to mollify critics around the world who want the United Nations involved, the United States and Britain are preparing a new Security Council resolution that would threaten military action if Saddam did not disarm.
This month, Iraq said it would permit the unconditional return of the arms inspectors, who left the country in 1998 and have not been allowed back. Washington, backed by Britain, has expressed scepticism, but Russia, China and France, the three other Security Council veto-holders, hailed the move.
China said on Tuesday it would consider the proposed resolution. "We have not seen the draft of the resolution. I think if there is such a resolution draft, we would be willing to study it," Foreign Ministry spokeswoman Zhang Qiyue said.
In Moscow, British ambassador Sir Roderic Lyne said he saw signs that Russia was moving closer to the British position and that in remarks on Monday, Defence Minister Sergei Ivanov was "clearly expressing openness" to a new UN resolution.
Russia's neighbours Ukraine and Belarus on Tuesday denied US allegations that their ex-Soviet arms stockpiles were being used to help Iraq amass weapons.
Washington said late on Monday it had stopped tens of millions of dollars in aid to Ukraine over an allegation that Kiev sold Iraq a "Kolchuga" system, which tracks moving objects on the ground and in the air when they emit radar signals.
Egypt's foreign minister, Ahmed Maher, said in remarks published on Tuesday that the Iraq crisis appeared to be easing now that Baghdad had agreed to the return of arms inspectors.
But oil prices continued to rise, partly on Iraq war talk. US benchmark crude oil futures jumped to their highest level since February 2001, up 61 cents to US$31.32 ($67.52) a barrel.
- REUTERS
Full text of the Blair dossier:
Iraq's Weapons of Mass Destruction
Further reading
Feature: War with Iraq
Iraq links and resources
