"And I think the almost undeviating support by Great Britain for the ill-advised policies of President Bush in Iraq have been a major tragedy for the world," Carter said.
Blair was in Baghdad yesterday morning for what will be his last trip to Iraq as British prime minister. Last week, Blair announced that he would step down June 27, making way for treasury chief Gordon Brown.
The war in Iraq has been the defining foreign policy issue of Blair's premiership, and the decision to join the US-led invasion was an unpopular one at home.
So far, nearly 150 British service members have died in Iraq.
Carter said Britain's support made it more difficult for critics of the war, and that the results might have been different if Britain spoke out against the 2003 invasion.
"I can't say it would have made a definitive difference, but it would certainly have assuaged the problems that arose lately," said Carter, who was president from 1977 to 1981.
"One of the defenses of the Bush administration, in the American public and on a worldwide basis -- and it's not been successful in my opinion -- has been that, OK, we must be more correct in our actions than the world thinks because Great Britain is backing us.
Carter took aim at the Bush administration's policy of preemptive war in Iraq, as well as its Middle East diplomacy, in a separate interview published yesterday in the Arkansas Democrat-Gazette.
"I think as far as the adverse impact on the nation around the world, this administration has been the worst in history," Carter said.
"The overt reversal of America's basic values as expressed by previous administrations, including those of George H.W. Bush, and Ronald Reagan, and Richard Nixon, and others, has been the most disturbing to me."
Carter gave the Arkansas interview while promoting his new audiobook series, "Sunday Mornings in Plains," a collection of weekly Bible lessons from his hometown of Plains, Ga.
"Apparently, Sunday mornings in Plains for former President Carter includes hurling reckless accusations at your fellow man," said Amber Wilkerson, Republican National Committee spokeswoman. She said it was hard to take Carter seriously because he also "challenged Ronald Reagan's strategy for the Cold War."
