An article yesterday said a Senate staff report on the recent bombing of the American Embassy annex in Lebanon "casts doubt on recent assertions that they had received specific, reliable intelligence warnings." The authors of the report, two staff members of the Senate Foreign Relations Committee, wrote that "we remain skeptical" about "speculation in the press" about such warnings and that "no specific warning was needed: all concerned knew that Lebanon was replete with explosives, readily available to those who had demonstrated a willingness to die while striking a blow against the American presence there." The article also should have noted that American intelligence officials, as reported last week in The Washington Post, said they had specific information days before the Sept. 20 bombing that explosives designated for use against American targets had been moved into Lebanon in mid-August. The officials also said they have warned of the possibility of another terrorist attack in Lebanon before the U.S. presidential election Nov. 6.

A Senate committee inquiry into the Sept. 20 Beirut embassy bombing says the attack succeeded because U.S. diplomats and security officers had failed to take one simple security precaution -- erection of a barrier -- and casts doubt on recent assertions that they had received specific, reliable intelligence warnings.

According to the bipartisan Foreign Relations Committee report, a visiting Defense Intelligence Agency team's survey of security in Beirut prior to the bombing "contained no intelligence findings or specific recommendations on security measures, and indeed did little more than recite what all concerned already knew: that Beirut is a dangerous place and buildings such as the U.S. Embassy annex are vulnerable to terrorist attack."

The CIA did know that Iranians operating nearby in Syria with diplomatic cover were "involved in the transport of explosives," but the report appears to cast doubt on whether the American operatives had a great deal more knowledge about just what the Iranians were up to.

A copy of the report, which is scheduled for release today, was obtained by The Washington Post. The report was distributed to members of the Senate committee yesterday.

The principal finding of the report was that the embassy complex in Christian east Beirut was vulnerable because of a "tragically simple mistake," the failure to install a substantial movable barrier to prevent a vehicle from passing until cleared. This, they say, could have been corrected easily either by the installation of swinging steel gates or by positioning heavy vehicles as temporary barriers.

The committee investigators, M. Graeme Bannerman and John B. Ritch III, professional staff representing the Rebublican majority and Democratic minority, respectively, were unable to determine why this was not done or whether anyone in the embassy had specifically raised it as a special problem in their on-scene investigation in the days immediately following the bombing.

But what they do add to the continuing examination of the attack is the context that has been missing from previous inquiries. They give vivid descriptions of the multitude of security and other problems American diplomats grappled with in the weeks and months before the attack.

Security officers had their hands full protecting embassy staff from kidnapings and assault. West Beirut, where the embassy long had been located, had turned into a state of mild anarchy following the takeover by Moslem militia and assorted street gangs in February. Christian east Beirut was far calmer, and clearly U.S. officials were anxious to move operations to what they regarded as its relative safety.

There was some dissatisfaction, however, about the site there. One embassy official worried endlessly about a rocket attack on the new structure. The facility's prominence on a high hill overlooking the Mediterranean caused others to worry about the possibility of a suicide attack from the air, perhaps one by a small, bomb-laden plane or glider.

The remodeling and security upgrading of the east Beirut facility progressed slowly, and the mission moved before it had been completed. One problem involved the local contractor for the new facility in Christian east Beirut. He was a Moslem, as many of his workers apparently were, and they faced chronic delays in clearing Christian militia checkpoints to get to work at the new facility. The committee investigators also felt the contractor was "spread too thin," doing similar work on a structure in west Beirut, where the United States had intended to keep a skeleton staff.

"All work seems to have been regarded as having equal priority," said the Senate report. "Thus, there was no particular pressure placed on the contractor by the embassy's administrative staff to focus special effort" on the installation of a permanent entrance gate.

The committee investigators reject the notion that diplomats would have been better protected if a Marine perimeter guard had stayed behind. They say the marines themselves were a target as is evidenced by the devastating attack on U.S. Marine headquarters last October.

The investigators also discarded conjecture that embassy personnel moved too hastily into the east Beirut facility, since the construction of a gate or other obstacle at the entrance was not especially time-consuming or difficult.

The report is most sharply critical, however, of the importance attributed to the Defense Intelligence Agency report seized upon by journalists after the bombing to make a case for negligence. The Senate investigators said the DIA did not appear to feel any particular urgency about circulating the report. The DIA team, which visited Beirut in July, only began circulating it immediately after the Sept. 20 bombing. Embassy personnel in Beirut did not get copies until after the bombing and after reports of the DIA's assessment had appeared in the press.

"The DIA report's release to the press, whatever the motivation behind it, added an unseemly and misleading element to public discussion of a tragic episode," the authors say.

The Senate report recommends that the number of American personnel in Lebanon be reduced to an "absolute minimum" but argues against shutting down the diplomatic mission, arguing that attacks on the United States probably would continue elsewhere.

The committee plans a similiar investigation after the election into how government agencies in Washington performed on the issue of security at the Beirut embassy.