Parliament, and not the Prime Minister, would make the final decision on taking Britain to war in future under proposals to be debated by MPs.
Clare Short, the former cabinet minister who is championing the move, yesterday claimed that she had the support of 200 MPs, including the Chancellor Gordon Brown.
The power to declare war was historically the prerogative of the sovereign, but has now passed to the Prime Minister, who has no obligation to gain the approval of Parliament.
After finishing third in the annual ballot to present a Private Members' Bill, Ms Short has won Commons time to table legislation requiring the support of MPs before hostilities begin.
She said: "In this day and age, to have the Prime Minister having the personalised power to sacrifice and take human life and not be properly accountable to Parliament, because long ago the king used to be able to do it, is not an adequate constitutional arrangement."
Although the Commons approved the Iraq war on the eve of fighting in March 2003, Ms Short, who quit the Cabinet in protest at the aftermath of the war, condemned the decision to invade as "undemocratic".
She said: "That vote came right at the last moment when the troops had already been deployed and, of course, Parliament and many other people, including myself, were misled about the legal situation."
Ms Short told Radio 4's Today programme: "The way the decision was made to go to war was very, very undemocratic, badly scrutinised, ill-thought through."
She argued that entrenching the right of Parliament to approve war would "improve the quality of decision-making and it would just be profoundly more democratic".
But the Labour MP Eric Joyce, a former Army officer who supported the war, said Ms Short's plan was unworkable. He said: "Ultimately, prime ministers and governments have to make decisions in certain circumstances very quickly with a strong imperative on quick action."Reuse content