British lawmakers in the ruling and main opposition parties alike sharply criticized Prime Minister Tony Blair's government on Monday for planning to dispatch hundreds of British troops to an area just south of Baghdad to supplement U.S. forces.

Speaking during a government presentation in the House of Commons, legislators accused U.S. forces of showing reckless disregard for Iraqi civilians and expressed alarm that the deployment of British troops would help free up the Americans for an all-out assault on the city of Fallujah. Some lawmakers also accused the Bush administration of seeking greater British participation as an election ploy to demonstrate to U.S. voters that there is international support for the Iraq campaign.

The criticism came not just from the war's long-standing critics, but from several of Blair's most ardent Labor Party loyalists. They contended that their leader is being dragged into a Vietnam-style quagmire by his close ally, President Bush.

"The United Kingdom has given 110 percent on this issue, and some of us have provided political cover and support for this government," said Andrew Mackinlay, a Blair supporter. He warned the government "not to try to stretch the envelope too much. . . . Some of us will not stomach it."

Gerald Kaufman, another Labor loyalist, raised "the possibility of United Kingdom forces risking their lives being exploited politically in a closely fought United States election."

Secretary of Defense Geoffrey Hoon, who fielded questions from the floor, said the deployment had been requested by American commanders in Baghdad and had nothing to do with U.S. politics. Hoon insisted no final decision had been made, but made it clear that the government would respond positively.

Asked by one lawmaker what the consequences of turning down the American request would be, he replied: "There will be no penalty, but we will have failed in our duty as an ally and as a country that has closely supported the United States."

While he gave no figures, newspaper reports said Britain would likely send 600 to 700 members of the Black Watch Regiment to the area just south of Baghdad.

Hoon's response caused one longtime Labor critic, Alan Simpson, to mockingly allude to a line from the musical "Oklahoma" in describing the government's position: "I'm just a girl who can't say no."

Britain maintains about 7,500 troops in the Basra region in southeastern Iraq, dominated by Shiite Muslims and a zone of relative tranquillity compared with the violence-wracked region around Baghdad where Sunnis form the majority.

British military commanders have cited their policy of comparative restraint in dealing with Iraqi civilians as one reason for the calm, and have privately been highly critical of American tactics and rules of engagement, especially during the first siege of Fallujah earlier this year.

"The last time the United States besieged Fallujah they left Iraq in an uproar over the many civilian casualties," said Robin Cook, who resigned from the cabinet last year to protest the war. He asked Hoon to consider the risk to British troops if they are seen by Iraqis as being responsible for civilian casualties.

Even people who have supported the war, such as Ian Duncan Smith, former leader of the Conservative Party, warned that British forces are subject to the newly established International Criminal Court for possible war crimes, while the United States has refused to submit to the court.

Nicholas Soames, the Conservatives' spokesman on defense, demanded "absolute assurance" that British troops would not be compromised by U.S. rules of engagement in dealing with civilians. Members of the Liberal Democrats, the third major party in the House of Commons, also expressed profound skepticism.

Hoon defended U.S. conduct, saying American forces had faced more dangerous circumstances than their British counterparts. He cited Soames's comment to the Sunday Times newspaper that "the concept of peacekeeping is one alien to our American friends," and added: "No doubt that will be read with great enthusiasm in the White House and in the Pentagon."