CHICAGO, SEPT. 26 -- President Bush today ordered a modest release of oil from the Strategic Petroleum Reserve and said he was prepared to take additional steps to stop speculators "who might try to drive up the price of oil."

White House officials called the release of 5 million barrels a test of the 590 million-barrel reserve, in anticipation of larger releases if shortages develop later this year. But they said they expected it would help dampen "unwarranted speculation" in world oil markets, which yesterday sent the price of crude oil to $38.67 a barrel on the New York Mercantile Exchange, more than double its $16.47 price last July.

"At home and abroad, let me caution those who might take advantage of the current crisis in the Persian Gulf, those who might seek profit by subverting the sanctions or -- here at home -- those speculators who might try to drive up the price of oil," Bush said in a speech at a Republican fund-raiser here.

Bush said that although world oil markets are tight because of the cutoff of production from Iraq and Kuwait, "there is sufficient oil to meet current needs."

But world markets have failed to take into account additional oil production from other countries that help to offset the production lost from Iraq and Kuwait, he said. "There is no justification for the intensive and unwarranted speculation in oil futures," he said.

Bush said that while he had authorized the release of just 5 million barrels, "I'm prepared to take additional steps, if necessary, to ensure that America stays strong right here at home."

The move comes amid a rising chorus of calls from Congress, oil economists and others for the administration to use the reserve to dampen prices that have been boosted sharply in recent days by oil-market speculation about future shortages.

Although Bush said last week he would consider a reserve drawdown to dampen price speculation, he and Energy Secretary James D. Watkins have repeatedly resisted using the reserve as a price lever, promising to consult with allies through the International Energy Agency. The IEA has not called for a stock drawdown, and said earlier this week that none was warranted.

Critics of pressure to release oil for price-control purposes have argued that doing so would signal speculators that the government expects a real emergency and would thereby drive prices even higher.

However, some analysts said last night it was unclear whether the one-time release of only 5 million barrels would have any immediate impact on prices. They noted it is less than one-third of U.S. daily consumption of 17 million barrels, but added it could have a symbolic effect by demonstrating the administration's commitment to hold prices down. It would also provide valuable experience in using the previously untapped emergency reserve, they said.

"I would guess this would have the effect of softening prices," said William Hermann, chief economist at Chevron Corp., the San Francisco-based oil giant. "If he {Bush} thinks the price is getting up too high, that's part of the cure."

White House press secretary Marlin Fitzwater said the government had announced the notice of the sale and would begin accepting bids. He said initial deliveries could take place in 15 days, with the entire 5 million barrels released in 30 to 60 days, but that schedule is uncertain because the procedure has never been tested.

The announcement followed a plea from Iran's minister of finance that all nations with oil reserves release them in order to help restore stability to international oil markets. However, the White House denied there was any connection between Bush's decision and the request from Mohsen Nourbakhsh, made at the annual meeting here of the World Bank and the International Monetary Fund.

The U.S. oil reserve is stored in salt caverns along the gulf coasts of Texas and Louisiana. The reserve, authorized in 1975, represents the largest stockpile of government-owned crude oil in the world and would supply U.S. demand for about 75 days at the current rate.

It was set up after the oil shocks of the 1970s in order to provide a supply cushion in the event of shortages. Congress voted earlier this month, over administration objections, to increase the maximum size of the reserve from 750 million barrels to 1 billion barrels. But no oil has been purchased since Iraq invaded Kuwait Aug. 2.

While world oil supplies have remained adequate since the invasion, prices have soared because of speculation that an outbreak of fighting could damage Mideast oil facilities and cause major shortages.

The United Nations embargo on shipments from Iraq and Kuwait has removed about 4.5 million barrels of oil a day from the world market, but much of that has been made up through increased production by Saudi Arabia and other nations. Statistics show that there is no significant shortage of crude oil.

In fact, the American Petroleum Institute said that U.S. inventories of gasoline, home heating oil and crude oil were all higher last week than in the corresponding week a year ago.

Fitzwater agreed there is "little shortage" of oil in the United States now, but said Energy Department officials are concerned that demand for home heating oil this winter could produce shortages.

Administration officials said the 5 million-barrel release would test the use of the reserve before serious problems develop. "We must make sure that we can act quickly, if necessary," Bush said.

Fitzwater called price increases a secondary reason for the test, but added that the administration "wanted to make clear to speculators that we do have oil available."

Fitzwater said that Bush, a former Texas oilman and proponent of free markets, had come to the decision to tap the reserve "reluctantly," adding that the administration still believes market forces should set prices. But he made clear the administration remains ready to move with larger releases if Bush's advisers believe that speculators are trying to take advantage of the gulf crisis.

Some experts have said the effect of opening the strategic reserve might be limited because of tightness in U.S. refining capacity, which could make it difficult to process any additional oil that comes on the market -- particularly the generally low-quality oil held in the reserve. "We may have some constraints in refining, and this would not help that situation at all," Hermann said.

"This is the one weapon {rising prices} the United States has to deal with in a marketplace fashion," said Edwin Rothschild, director of Citizen Action, a Washington-based consumer advocacy group. "Let's hope the whole process works out so that if we do have to use it in any significant way, we do have the operational know-how to use it properly."

Balz reported from Chicago and Potts from Washington. Staff writer Thomas W. Lippman contributed to this report from Washington.