White House, intelligence and Pentagon officials say they still do not know who carried out the terrorist bomb attack on the U.S. Embassy in Beirut on April 18 in which 63 people, including 17 Americans, were killed.

Despite some recently broadcast and published reports of evidence linking the bombing to the government of Iran, senior officials here say there is not enough hard evidence at this time "to point the finger at anyone."

"The agencies are still sifting through a lot of intelligence, and haven't yet reached any firm conclusions as to who was responsible," said one senior intelligence official.

A well-placed White House official echoed that assessment. Both officials, and others interviewed, emphasized that they were not ruling out Iranian involvement in the bombing. Rather, they were saying, as the White House official put it, "that we don't know precisely. We don't have enough information to make that charge."

Officials say the Iranians remain the most plausible suspects, and that in the aftermath of the disaster there was a "considerable desire" by some, as one source put it, to blame Iran. But there are other suspects, including Libya and Syria and groups of Lebanese and Iraqis who are pro-Iranian.

Immediately after the bombing a little-known terrorist group calling itself the Islamic Jihad, or Holy War, claimed responsibility in telephone calls to some news organizations in Beirut and said the attack was part of the Iranian revolution against imperialism. But other news organizations got calls from other groups claiming responsibility.

On May 10, columnist Jack Anderson reported that U.S. intelligence had picked up warnings a month in advance, in electronic interceptions, that a pro-Iranian Shiite Moslem group loyal to Ayatollah Ruhollah Khomeini was planning to bomb the embassy and that the scheme was supervised from the Iranian Foreign Ministry.

On May 16, CBS television news reported that U.S. intelligence "has evidence linking the government of Iran" to the bombing.

CBS said one intercepted cable from the Iranian Foreign Ministry to the Iranian Embassy in Damascus, Syria, approved a $25,000 payment for a terrorist attack on an unidentified installation in Beirut. Another cable reportedly paved the way for passage of 12 Iranians through Damascus to Beirut. CBS also reported that these same 12 Iranians then reappeared in Damascus several hours after the attack, just long enough to have made the drive between the two cities.

Yesterday, Iran's official news agency branded as "lies" allegations that it was involved in the bombing.

The CBS report has caused considerable concern within the government because it deals with the sensitive content of intercepted cables. Pentagon sources say an investigation has been launched by the CIA and the National Security Agency, the agency that handles electronic eavesdropping.

When asked about these reports, official privately confirm that there were cables intercepted, and they suggest that one of them did involve a payment for a would-be terrorist action. "But who knows for what and when," one White House official said.

There was no such confirmation as to the dozen Iranians who supposedly passed through Damascus. All officials interviewed said they had not seen reports of 12 individuals reappearing in Damascus after the attack.

A White House official said that the information upon which the broadcast report was based "was not accurate enough or substantial enough to make that charge" about evidence linking the action to Iran. Officials described the report as "partially accurate, partially inaccurate and partially distorted."