Authorities in Yemen and Jordan have broken up plots by Iraqis who were preparing to bomb Western targets in those nations in recent days, and the United States has warned 10 other countries that small groups of Iraqi intelligence agents are readying similar attacks against Americans and other Westerners, according to U.S. government officials.

Yemeni authorities raided a house in the capital city of Sanaa Wednesday night, where they arrested a small group of Iraqis and seized a cache of explosives that they believe were to be used against the U.S. and British embassies. At about the same time, authorities in the Jordanian capital of Amman arrested a group of Iraqis, also with explosives, who were preparing to bomb a hotel frequented by Westerners, the officials said.

State Department spokesman Richard Boucher said yesterday that, "in both cases, operatives were arrested and terrorist material confiscated. The planned attacks were not successful." Boucher did not name the nations where the attacks were thwarted.

U.S. intelligence agencies have also learned that similar bomb plots have been planned in at least 10 other countries, among them Britain, Pakistan, Turkey and Syria, the officials said. The United States was not among the countries targeted, they said.

A senior intelligence official said yesterday that there was no evidence that the Iraqis involved in the current plots had made any contact with al Qaeda or other terrorist groups. "This was Iraqi state-sponsored terrorism," one official said.

U.S. government officials declined to discuss how they learned of the Iraqi cells, but they have been watching for such attacks as the nation headed toward war with Iraq. Iraqi President Saddam Hussein tried to launch similar attacks during the 1991 Persian Gulf War.

Based on that experience, orders went out earlier this year to CIA officers and FBI agents abroad to contact local security officials and arrange for the surveillance of Iraqi intelligence officers who might be planning similar bombings should war break out. In October, CIA Director George J. Tenet told Congress that if Hussein was convinced that war was inevitable, he "probably would be less constrained in adopting terrorist actions."

"The arrests came as no surprise," a senior intelligence analyst said yesterday. "We are watching now to see how much more effective they may be this time."

The intelligence services in the countries where information indicates attacks may be planned have been warned of the plots, and the United States is reiterating its requests that they expel Iraqi diplomats. Yesterday, a senior administration official said he did not want to identify all the countries because efforts were still underway to get the local security services to move against the potential attackers who are still at large.

None of the 1991 bombing attempts -- planned for more than a dozen countries around the world, including Australia, Thailand and the Philippines -- was successful. At that time, Hussein sent pairs of agents to numerous countries, where they picked up explosives or weapons that had been sent ahead.

Almost all the Iraqi agents were identified, however, because they carried sequentially numbered passports. After the first few were identified and questioned, it was easy to locate the others.

After the 1991 war, former CIA director William H. Webster told a congressional committee: "At our request these teams were picked up; they were interrogated; they were arrested where there was cause to do so; and when there were no legal grounds for arrest they were deported."

In the United States, the FBI has completed more than 7,000 interviews with Iraqi-born immigrants and citizens since the war in Iraq began, part of a broad wartime contingency plan aimed at gathering intelligence and guarding against threats to U.S. targets.

In an October letter to Sen. Bob Graham (D-Fla.), then-chairman of the Senate Select Committee on Intelligence, Tenet predicted that the Iraqi leader "might decide that the extreme step of assisting Islamist terrorists in conducting a WMD [weapons of mass destruction] attack against the United States would be his last chance to exact vengeance by taking a large number of victims with him."

FBI Director Robert S. Mueller III told a House subcommittee on Thursday that the interviews have yielded valuable information that is "very helpful to those who are now in the war in Iraq." Many of those interviewed are dissidents critical of the Hussein government, officials said.

"What we have found, in our interviews around the country, is a wealth of information from those who have spent substantial time in Iraq and have learned the location of bunkers or telecommunications networks or structural information," Mueller said.

Staff writer Dan Eggen contributed to this report.