U.S. Had Received Threats Against Personnel in Saudi Arabia : Mideast: Security was unchanged because nation has been one of world’s ‘safest,’ ambassador says.

The United States received threats against its diplomatic and military personnel in Saudi Arabia prior to Monday’s deadly bombing but decided not to alter security arrangements because the desert kingdom has been among the world’s “safest places,” U.S. Ambassador Raymond Mabus said in Riyadh on Wednesday.

U.S. intelligence has also been aware for several months that Iranian agents put U.S. facilities and personnel in Saudi Arabia under surveillance--apparently as part of a wider intelligence operation in the Mideast and elsewhere, senior U.S. officials in Washington said. But the U.S. reports did not lead to a heightened state of alert in Riyadh.

An explosion at the U.S.-run national guard headquarters in the Saudi capital killed seven, including five Americans, and injured 60.

The most specific threats were from the Movement for Islamic Change in the Arabian Peninsula-Jihad Wing, which faxed warnings to Western embassies as well as to groups outside the country.

It vowed to attack U.S. interests with “all available means” unless the “crusaders” left Saudi Arabia.

The U.S. embassy’s Emergency Action Committee investigated the threats but was unable to “find anyone behind the faxes,” which were sent in April and June and called for a Western pullout by July, Mabus said.

“We take these things seriously and do what is necessary for security,” he said. “[But] you cannot let somebody with a fax machine paralyze you or keep you from doing what you do day-to-day.”

The movement had no known background and no track record of violence. Other groups have made similar threats against Americans but never followed through.

Because of the sheer number of threats against a wide variety of U.S. personnel and interests abroad and at home, not all can be traced or verified, Pentagon sources said.

One Saudi group now under close scrutiny is the Committee for the Defense of Legitimate Rights, a group of Muslim jurists and academics whose leadership is in exile in London.

U.S. investigators are looking into whether the faxes to the American Embassy in Riyadh from the Movement for Islamic Change came from the Committee for Rights’ London office.

In interviews Wednesday, the two ranking committee officials in London denied any such links, noting that they have been faxing their own newsletters to the Riyadh embassy for years--at U.S. request.

The group charged that the Saudi government or others were framing it because it does not list its fax number on transmissions. Because it is now the largest opposition group, the House of Saud views the committee as its most serious challenger.

After the bombing Monday, the group condemned the attack and other uses of violence to promote change.

But spokesman Mohammed Masari said in an interview Wednesday that he considers U.S. troops in the kingdom to be “a foreign occupying army supporting an illegitimate government.”

Meanwhile, a growing number of U.S. officials are hinting that a foreign power may have been involved in the blast.

Echoing early speculation in Washington, Mabus told reporters that neighboring Iran may have played a role in the explosion.

“I’ve got a very open mind as to who might be involved, but . . . we have some bad neighbors. . . . [Iran] is one of them,” he said.

U.S. officials are quick to add, however, that there is no concrete evidence indicating which individuals, groups or governments are responsible--and there may be none for a long time.

To expedite the investigation, Saudi Arabia pledged an $800,000 reward for information about the perpetrators.