President Bush on Monday hailed the capture of an al Qaeda leader in Iraq, as the White House moved to defend U.S. intelligence capabilities after several government officials said Saddam Hussein may not have had weapons of mass destruction.

"Just last week we made further progress in making America more secure when a fellow named Hassan Ghul was captured in Iraq," Bush said, drawing attention to an arrest the administration announced last week. "Hassan Ghul reported directly to Khalid Sheik Mohammed, who was the mastermind of the September 11th attacks . . . . He was captured in Iraq, where he was helping al Qaeda to put pressure on our troops."

Bush's remarks, made here at a hospital renewing his call for curbs on medical malpractice awards, added to the administration's assertions that the invasion of Iraq was justified even if the country did not have forbidden unconventional weapons.

"Let me just say that the decision to remove Saddam Hussein's regime from power was the right decision," press secretary Scott McClellan said aboard Air Force One. He had been asked about claims by the former chief U.S. weapons inspector in Iraq that Hussein apparently did not have stockpiles of chemical and biological weapons and had only a rudimentary nuclear program. McClellan declined to repeat earlier White House assurances that such weapons would be found.

The doubts by the former inspector, David Kay, who resigned Friday as head of the Iraq Survey Group inspection team, were echoed over the weekend by other prominent officials. They included Sen. Pat Roberts (R-Kan.), chairman of the Senate intelligence committee, and Secretary of State Colin L. Powell, who said it was possible Iraq did not have stockpiles. Kay suggested that U.S. intelligence had failed by not realizing Iraq's weapons program was in chaos and its scientists were lying to Hussein to get funds.

McClellan said a portion of Kay's remarks "only reconfirms that the president made the right decision" to invade Iraq. "Dr. Kay said the regime continued to pursue a biological weapon, including the deadly poison ricin," and "continued an active ballistic missile program."

McClellan said the White House would reserve judgment on whether Iraq had prohibited weapons and whether U.S. intelligence misled the White House. "Obviously, we want to compare the intelligence from before the war with what the Iraq Survey Group learns on the ground," he said.

On Capitol Hill, Senate Minority Leader Thomas A. Daschle (D-S.D.) called for an investigation into the "administration's role in the intelligence failures leading up to the war with Iraq."

Bush made no reference to the weapons controversy in Monday's speech and has not taken questions since Kay began to voice his doubts Friday. But others in the administration said the arms, originally the main justification for war, were not all-important. Attorney General John D. Ashcroft said Monday that concerns such as Iraq's "evil chemistry and evil biology" justified war even without the weapons.

Bush has said previously there is no evidence that Hussein had a role in the Sept. 11, 2001, attacks. Vice President Cheney, however, in an interview this month with the Rocky Mountain News, recommended as the "best source of information" an article in the Weekly Standard magazine detailing a relationship between Hussein and al Qaeda based on leaked classified information. The Pentagon had previously called the report's conclusions "inaccurate" and said the leak of raw intelligence data does "serious harm to national security."

Retired Gen. Wesley K. Clark, a presidential candidate, said on NBC's "Meet the Press" Sunday that Cheney was "essentially using a leaked memo to confirm his predisposition to believe that Saddam had something to do with 9/11." Clark said the "standard rule on anything like this is never to confirm it because if you confirm something like this, you're giving away maybe sources and methods." Cheney's office did not respond to Clark's comments.

Though Bush on Monday did not assert that Iraq was culpable in the Sept. 11 attacks by al Qaeda, identifying Ghul as reporting to Khalid Sheik Mohammed suggested an indirect link. Many Americans believe Iraq had a role in the terrorist attacks on the World Trade Center and the Pentagon, which has bolstered support for the U.S. occupation of Iraq. Intelligence experts have generally disputed any connection between Iraq and the Sept. 11 attacks.

Monday, Bush mentioned Iraq only in the context of Ghul's capture. "He was a part of this network of haters that we're dismantling," the president said. Ghul, a Pakistani who was believed to be scouting for attacks on U.S. troops, was captured last week in northern Iraq by Kurdish forces.

Bush's assertion Monday that medical malpractice lawsuits are a "major cost driver" in the U.S. health care system is disputed by a recent Congressional Budget Office report. It concluded that "even large savings in [malpractice] premiums can have only a small direct impact on health care spending -- private or governmental -- because malpractice costs account for less than 2 percent of that spending."

Staff writer Amy Goldstein in Washington contributed to this report.