The United Nation's first attempt at a full-scale investigation of the human rights situation in Iran has concluded, in a report released today, that widespread allegations of systematic executions and torture "cannot be dismissed as groundless" and continued monitoring is called for.

The interim report, prepared for the General Assembly by Andres Aguilar of Venezuela, a special representative of the U.N. Human Rights Commission, was leaked by representatives of the Bahai religious community and will be issued officially next week.

The Bahais termed the Aguilar report a whitewash that "will cut the feet out from under U.N. action to pressure Iran to limit rights violations," in the words of Richard Fursland, a consultant to the group. He served until recently as the British representative on the Human Rights Commission.

Fursland's view was echoed, in lower key, by a number of western diplomats now drafting an assembly resolution on Iranian violations. The assembly will have Iran and Afghanistan on its human rights agenda for the first time, in a debate slated to start next week.

Aguilar reported that Iran had not permitted him to enter and had not responded adequately to the allegations he cited. But he did not draw any conclusion as to the truth of the charges, and expressed appreciation for Iranian "cooperation."

The U.N. representative's job, said one western diplomat, "is supposed to be to make conclusions on what may be true, and he was too cautious in saying nothing is proven."

Another member of the drafting group noted that the evidence available -- including documented cases by Amnesty International that were not in the Aguilar report -- "is certainly enough to support stronger conclusions."

Several members said their job would be more difficult because U.N. resolutions are generally based on such reports, and "there is little in this report to take hold of."

The diplomats, however, agreed that the report would serve as a basis on which the assembly could ask Iran for better cooperation in monitoring rights violations and could legitimize reconsideration of the issue at future U.N. sessions. They seemed satisfied that the pressure would remain on Tehran to moderate its internal repression.

Fursland noted that he helped draft the original resolution establishing Aguilar's mission and "the idea was a substantive report on what the Iranians were doing." Now that the report makes a strong, condemnatory resolution less politically feasible, he said, "Iran will see it as a green light to step up persecution of the Bahais and others."

Representatives of the Bahai faith, which originated in 19th-century Iran as an offshoot of Islam and now has about 300,000 adherents there, said that about 300 of their number have been executed thus far, and all have been subjected to "a concerted campaign of religious persecution."

In their response to Aguilar, Iran insisted that no one is prosecuted for belief in Bahaiism, but organizations that propagate "corruption and [an] overt campaign against Islam . . . may be considered as detrimental to national security . . . and membership [in] such organizations could be considered as a crime."

The U.N. report also considered allegations by representatives of the Mujaheddin organization, which seeks the overthrow of Ayatollah Ruhollah Khomeini.

It did not deal directly with rights issues relating to the Iranian-Iraqi war, such as the treatment of Iraqi war prisoners.

Aguilar made no attempt to quantify the allegations of violations, and was specific only about interviews he conducted in July with 13 persons who claimed to be victims.