Blair, ending a weekend of talks with President George W. Bush, urged the international community to confront terrorist regimes with military force if necessary then called Saddam a brutal leader who must be dealt with. He stopped just short of specifically threatening military action against Iraq.
"The regime of Saddam is detestable," the prime minister told more than 1,000 people at the presidential library of Bush's father, the 41st president, in College Station, Texas. The elder George Bush, who introduced Blair, pushed back Iraq's 1990 invasion of Kuwait, but was criticized for ending the Persian Gulf War with Saddam still in power.
Blair's aides said the Iraq remarks were a last-minute addition to his speech, drafted Saturday night and Sunday morning while the prime minister visited Bush at the president's nearby ranch. The strong language, coming at a time when Blair is under pressure in Britain to distance himself from Bush's war talk, was viewed by White House aides as needed reaffirmation of the close U.S.-British alliance against terrorism.
Bush repeatedly says all options are on the table for dealing with Saddam, a characterization that aides say includes possible military action. The president calls Saddam a threat to the world, accusing him of producing weapons of mass destruction that could be used by Iraq's terrorist allies.
Many foreign leaders, including U.S. allies, worry about Bush's intentions. Chinese President Jiang Zemin, in remarks published Sunday, urged the United States to refrain from military action against Iraq. "International disputes cannot be solved by force," Jiang said.
Blair, talking broadly about his approach to fighting terrorism, not just Iraq, said, "If necessary, the action should be military and again, if necessary and justified, it should involve regime change." Bush uses "regime change" to describe what he has in store for Saddam.
Blair quickly followed the general warning with a specific one to Saddam: "He has to let the inspectors back in anyone, any time, any place the international community demands." Saddam has blocked the promised U.N. inspections.
"To allow weapons of mass destruction to be developed by a state like Iraq ... would be grossly to ignore the lessons of Sept. 11, and we will not do it," he said.
Blair suggested that any action against Saddam will not occur right away.
"We will proceed, as we did after Sept. 11, in a calm, measured, sensible but firm way," he said.
Like Bush, the prime minister said terrorism can be curbed not just by military action, but also by cutting off financing to groups such as al Qaeda. Military action is not the only option for Saddam; he could be undercut by diplomatic pressure or covert backing of internal opponents, U.S. officials say.
"The president has not decided to use military force," National Security Adviser Condoleezza told CNN before attending Blair's address. "There may be other things that can be done.
Urging world leaders to stand ready against terror, he said: "We cannot, of course, intervene in all cases... but where countries are engaged in terror or the (weapons of mass destruction) business, we should not shirk from confronting them," he said.
He said nations such as Syria, Iran and North Korea still can change enough to avoid retribution. But he seemed to hold out little hope for Iraq.
"It is a regime without a qualm in sacrificing the lives of its citizens to preserve itself," he said.
Bush has grouped Iran, Iraq and North Korea in an "axis of evil."
Blair spent parts of three days on Bush's Crawford, Texas, ranch to discuss Iraq and the mounting crisis in the Middle East.
At the Bush library, Blair urged the Saudis to put in the form of a U.N. resolution its proposal to offer Israel "normal relations" in exchange for a full withdrawal from Arab lands held since 1967.
Blair viewed the call as a way to throw his support behind the principles of the Saudi plan, but not necessarily every detail of the proposal, a spokesman said.
Afterward, he took questions from the audience, including one about Britain's support of a global climate change treaty that Bush rejected.
"Look, we've got different positions on this," Blair said with a chuckle, not wanting to challenge the president in his home state. "But I do think this is one of the biggest issues that we face as a world today."