Saddam Hussein is able to deploy chemical and biological weapons within 45 minutes, the prime minister told a packed House of Commons yesterday.

The MPs heard that Britain has put together an "overwhelming" case against the Iraqi leader.

The much anticipated dossier stated that Iraq had resumed production of chemical and biological weapons, as well as attempting to purchase "significant quantities" of Uranium in Africa.

In his statement to MPs, Tony Blair said: "We know... from our history that diplomacy not backed by the threat of force has never worked with dictators and never will work."

But his appeal failed to face down rebels within his own ranks - with 53 Labour MPs trooping through the lobbies last night to register their opposition to a war with Iraq.

Iain Duncan Smith offered his party's support, saying: "Those who refuse to contemplate military action at any price must ask themselves how we are to force Saddam to comply with resolutions that he has flouted for a decade."

But several of his MPs broke ranks to warn against a war. Douglas Hogg and Edward Leigh both expressed concern.

Charles Kennedy also expressed fears. To audible murmurs of approval from Labour MPs, he said it was a matter of "deep concern" that the United States may not believe that the emphasis had to be on getting UN weapons inspectors back into Iraq.

In the House of Lords senior politicians, bishops and military chiefs called on Blair and president Bush to ensure they put in place a long-term strategy for Iraq's future before embarking on military action.