In a 50-minute address to a packed House of Commons, the prime minister outlined his case for attacking Iraq.

After admitting that his government was facing its most serious test, with its majority at risk for the first time since he came to power, Tony Blair described in detail the scale of Iraq's weapons.

He insisted it was time to end the 12 years of "games" being played by Saddam with the international community.

Describing the Liberal Democrats as "unified as ever in opportunism and error", the prime minister said that Britain could not afford to back down in the face of the "clear and present danger" to its national security.

To retreat now would "tell our allies that at the very moment of action, at the very moment when they need our determination, that Britain faltered".

"I would not be party to such a course," he said in what was seen as a back me or sack me threat.