NEW YORK (CNN/Money) - Oil prices fell even as President Bush's called Thursday for action against Iraq.

In a speech at the United Nations, Bush said that the international body should force Iraq to comply with disarmament pledges and other past promises, but said the regime of President Saddam Hussein could not be trusted and must be removed. He made clear that the United States was prepared to act by itself against the country if the United Nations did not take action. The U.S. government earlier released a report it said documented Iraqi violations of U.N. resolutions.

The president's speech followed remarks by U.N. Secretary-General Kofi Annan calling for Iraq to allow weapon inspectors to return to the country for the first time since they were expelled by Iraq in 1998. But he warned that the United States should not take unilateral action against Iraq.

Oil prices have climbed continually in recent weeks and months the face of talk of U.S. action against Iraq, which was seen possibly affecting the world supplies of oil. But Thursday the prices fell in reaction to Bush's remark.

In U.S. trading, a price of a barrel of light crude oil for October delivery fell 97 cents to $28.80, after being down only 4 cents before the speech began. The price for Brent crude was down 91 cents to $27.48 in London trading, after being up 6 cents before the speech began.

"I think that oil has had a nice runup for the last three-to-four weeks in preparation for the speech," said Michael McAllister, oil analyst for Fahnestock & Co. "Now the news is out there, and they're seeing maybe the runup is not warranted."

McAllister said that some oil traders perhaps were expecting Bush to actually set a deadline for action, which the president did not do. But McAllister doesn't believe the content of the speech was seen as more or less of a threat to oil supplies than expectations, or that the situation is just an example of investors buying on rumor and expectation and selling on the news.

"It may not have mattered what was said," he said.

The major U.S. stock indexes, which were all off more than 1.5 percent before Bush began to speak, were little changed during and after his remarks. Stock prices seemed to be reacting more to congressional testimony by Federal Reserve Chairman Alan Greenspan about the state of the economy than to the president's remarks at the U.N. gathering.