Arab diplomatic efforts to end Iraq's occupation of Kuwait stalled yesterday as President Bush stepped up efforts to cut off Iraq's oil-export pipelines through Turkey and Saudi Arabia until Iraqi President Saddam Hussein withdraws his 100,000-man invasion force and allows the return of Kuwait's rulers, administration officials said.

At the same time, Saudi Arabia was said by U.S. officials to be mobilizing its air and ground forces to confront any Iraqi invasion that might be mounted from Kuwait toward Saudi oil fields.

A U.S. military official said small Iraqi mobile units crossed the Saudi border several times during the day and then returned to Kuwait. U.S. analysts could not discern whether the crossings, which went unchallenged, were inadvertent or deliberate probes. Iraqi forces were also reported to have looted expensive villas and searched homes in the so-called Neutral Zone, a disputed area along the Saudi-Kuwaiti border.

The Iraqi invasion of the small sheikdom of Kuwait on Thursday has presented leaders around the world with the first major crisis of the post-Cold War period. The Soviet Union, Japan and the European Community have joined the United States in a broad array of economic and military sanctions, and French and British and U.S. warships steamed toward the Persian Gulf.

But none of these measures has prevented Iraq from consolidating control in Kuwait -- where Iraq yesterday announced the formation of a new military government and a new army -- or menacing Saudi Arabia.

U.S. contingency plans to respond to a full-scale Iraqi attack on Saudi Arabia were said by military officials to include the deployment to the Middle East of F-117 Stealth fighters and B-52 bombers, which would be used to inflict massive damage on Iraq's military and industrial centers and, ultimately, its oil installations.

The Pentagon also has dispatched special operations forces and hostage rescue forces, including elements of the Delta Force, to the Middle East in the event that they are needed to extract Americans trapped or taken prisoner in the conflict, officials said. There are currently an estimated 3,000 Americans in Kuwait and 500 in Iraq.

Iraq's ambassador to Washington said late yesterday that 11 of 14 Americans reported missing in Kuwait since the invasion have been released in Baghdad. A State Department official said the original estimate of 14 Americans missing may have been wrong and the release of the 11 oil workers may be a total accounting for the missing.

One State Department official said U.S. Embassy officers in Baghdad are talking to oil workers at a hotel there and a daughter of one worker said they were to be flown out of Iraq as soon as possible.

Bush met with his senior advisers at Camp David for two hours yesterday morning and the White House later issued a statement saying the president "again expressed his concern for the safety of American citizens" in both Kuwait and Iraq.

"We continue to seek the immediate, complete and unconditional withdrawal of Iraqi forces from Kuwait and restoration of the legitimate government of Kuwait," the statement said. It reiterated that "all U.S. options are under consideration."

Tens of thousands of Iraqi troops backed by hundreds of Soviet-made tanks remained stationary in the desert southwest of the Kuwaiti capital in a formation that U.S. intelligence officials said was oriented for combat at the Saudi frontier.

One source said the Pentagon for the first time had begun sharing U.S. reconnaissance satellite photos with the Saudis to help them with defensive preparations. Those efforts center around the King Khalid Military City complex, built with U.S. assistance, in northeastern Saudi Arabia.

Kuwait's ambassador in Washington, Sheik Saud Nasir Sabah, said yesterday that 800 Kuwaitis were killed or injured during the Iraqi invasion, which followed two weeks of charges from Baghdad that Kuwait had stolen oil from Iraq and was responsible for a fall in oil prices.

The U.S. plan to cut off Iraqi oil exports was deemed the most immediate and painful leverage the West could bring to bear against Saddam and the best hope to reinstate the government of Kuwait's emir, Sheik Jabir Ahmed Sabah. The emir fled to Saudi Arabia as his country was invaded and Iraq has said he will not be allowed to return.

Iraq yesterday announced nine members of what it called the "Provisional Free Government of Kuwait," which was denounced as a puppet regime by foreign nations. The leader was identified as Col. Ala Hussein Ali, whose background was not provided by Iraqi officials. In Washington, Kuwait's Ambassador Sabah said the nine were Iraqi military men.

Also Saturday, Baghdad Radio broadcast a communique from the provisional government announcing that it was creating a Kuwaiti army that would accept all Arab nationals "who wish stability for Kuwait in its new age." Iraqi television said more than 100,000 Iraqis had volunteered.

Efforts by Arab leaders to mediate the conflict stalled when talks scheduled to be held in Saudi Arabia yesterday failed to materialize. Saddam on Friday had agreed to attend the session, along with Saudi Arabia's King Fahd, Egyptian President Hosni Mubarak, Jordan's King Hussein, Yemen's President Ali Abdallah Salih and Kuwait's Sabah.

There were conflicting reports on whether Sabah refused to meet with Hussein while Iraqi troops occupied Kuwait, or whether Saddam refused to attend on the grounds that Kuwait's ousted rulers might try to kill him. Jordanian King Hussein suggested in a British television interview that Saddam was angered by an Arab League condemnation of the Iraqi attack, saying that the criticism had ruined the plans for the summit.

Meanwhile, more nations around the world joined an effort to isolate and punish Iraq, with the European Community yesterday announcing an embargo on oil imports from Iraq and Kuwait. The EC also agreed to freeze Iraqi assets and halt arms sales to Baghdad in what was called a near total commercial embargo on Iraq. The United States, Japan and individual European countries already had frozen Kuwaiti or Iraqi assets and taken other economic measures to punish Iraq, and the Soviet Union has cut off arms supplies to Baghdad.

A senior U.S. administration official said the push to cut Iraq's oil output immediately is a key element of a strategy that includes trade sanctions, arms embargoes and United Nations Security Council authority to enforce its resolution calling for Iraq's unconditional and immediate withdrawal from Kuwait.

A second official described the U.S. approach as an urgent "containment policy" to strangle Saddam's financial lifelines and his military supply line. "When you cut him off, hit him where he lives, the seeds in discontent in Iraq will not be long in coming," the official said. "It won't take . . . long; he needs a lot of weapons" and the oil revenue to buy them.

Iraqi broadcasts warned yesterday that if any foreign power intervened in the Persian Gulf, Iraq would "chop its arms off from the shoulders."

Iraq exports 1.5 million barrels of crude per day through the pipeline that crosses Turkey to the Mediterranean. Two Iraqi pipelines through Saudi Arabia can carry 1.65 million barrels per day. Together, the pipeline volumes equal the total quota of crude oil Iraq is allowed to export by the Organization of Petroleum Exporting Countries.

Neither Saudi Arabia's King Fahd nor Turkey's president, Turgut Ozal, has given approval to cut the Iraqi oil pipelines that pass through his country, but Bush was said by administration officials to be using quiet persuasion that would allow them to initiate or acquiesce in the shutting off of Iraq's oil output.

Said one source involved in the Arab diplomatic efforts: "Certainly for the Saudis to do it would be a casus belli {for Iraq to invade} and the Saudis are not convinced that they have exhausted the Arab and Moslem diplomacy."

Ozal yesterday responded to Bush's Friday statement that cutting off the pipeline was an option by saying: "There has been no demand from the United States for the closure of the pipeline. Such a demand is out of the question."

An administration official said Bush told Ozal that "we should all stand together" against Iraq and that bringing swift pressure on Saddam was "the right thing to do."

Administration officials said Bush did not make a specific pledge that the United States would help defend Turkey against an Iraqi attack over the pipeline because Turkey is a member of NATO, whose credo states that an attack on one member is an attack on all.

The United States has aircraft carrier battle groups steaming toward Turkey's Mediterranean coast and the Arabian Sea.

Iraq's ambassador here, Mohamed Mashat, said yesterday that it "is absolutely not true" that Iraqi forces have entered the Neutral Zone on the Saudi border.

Kuwait's Ambassador Sabah, referring to Iraq's pledge to begin removing its troops, said, Saddam "does not intend to withdraw." He said Iraqi forces have "dug in" in the south, and have taken over the Central Bank.

Staff writer David Hoffman in Washington contributed to this report.