The U.N. fact-finding commission on Iran left Tehran in defeat after top-level U.S. and U.N. officials rejected a last-minute proposal requiring that the panel approve a statement charging past American interference in Iranian affairs, diplomatic sources said yesterday.

If the commission had signed the statement, its five members would have been promised a rare meeting with Ayatolah Ruhollah Khomeini and a visit with the American hostages, according to this report of the plan proposed a few hours before the panel left Tehran early yesterday morning.

Sources close to Iranian President Abol Hassan Bani-Sadr and Foreign Minister Sadegh Ghotbzadeh said the plan put forth by Ghotbzadeh in the panel's Tehran hotel suite at 1:30 a.m. represented a reasonable chance of breaking the deadlock over a visit to the hostages.

But U.N. Secretary General Kurt Waldheim suggested in an interview with the The Washington Post that any effort may have been stymied by the same difficulty that has undercut earlier attempts to solve the 129-day occupation of the U.S. Embassy in Tehran.

"The whole thing boils down to this -- the Iranian government couldn't deliver," said Waldheim. The U.N. chief had devised the package deal calling for release of the estimated 50 hostages in exchange for the commission's investigation of Iranian grievances.

Waldheim praised Iranian government leaders for trying to settle the crisis, but said he regretted their inability to draw support from Khomeini, the nation's revolutionary leader who wields the only control over the militant embassy captors.

Despite the cooperation of Iranian authorities, he said by telephone from New York, the commission will withhold a report on its 17-day inquiry until the officials make good on their promise to arrange a meeting between the panel and the hostages.

The commission's mandate sanctioned in writing by Bani-Sadr called for humanitarian visits with each of the hostages. It specifically ruled out the kind of "interrogations" that were demanded by Khomeini in a statement yesterday that led to the panel's departure.

Waldheim finally decided to recall the commission after a flurry of long-distance telephone calls to Tehran and Washington to discuss Ghotbzadeh's 11th-hour scheme to salvage the mission before the panel left for home.

In Suite 1001 of Tehran's Hilton Hotel, Ghotzabeh pleaded with the five lawyers to stay another day and follow a new plan that would lead to their visit to the embassy and release of the American captives within two weeks, according to sources.

The commission would meet with Iran's governing Revolutionary Council, Ghotbzadeh proposed, and then endorse a joint statement blaming the United States for past interference in Iran through its support for deposed Shah Mohhamad Reza Pehlavi, sources said.

Once the commission agreed to the statement, the members would be taken to see Khomeini, the one Iranian figure who could break the hostage deadlock. Within a short time, they would meet all of the hostages, according to Ghotbzadeh's new formula.

In a succession of telephone calls between Waldheim and the commission in Tehran and Waldehim and U.S. Secretary of State Cyrus R. Vance in Washington, it was decided to push for a meeting between the panel and the Revolutionary Council, sources said.

But Vance and Waldheim refused to allow the commission to ratify the anti-American statement, maintaining that such a concession exceeded terms of the package deal. Moreover, there were no guarantees that this latest Iranian promise would be fulfilled.

"It was like buying a pig in a poke," said a source close to the commission, who added that the panel may have considered the plan at an earlier stage in its visit but had become too compromised by the sudden reversals and broken promises of recent days.

But Washington Post correspondent Jonathan C. Randal reported from Tehran that sources with knowledge of the early-morning negotiations said that two commission members blocked Ghotbzadeh's proposal by insisting that the panel leave as soon as possible.

These sources, at least one of whom was present during the frantic talks at the Hilton, said the two commissioners turned down personal appeals from Waldheim and President Carter's chief of staff, Hamilton Jordan, to stay and make one more effort.

Sources said the split in commission ranks became apparent shortly after Ghotbzadeh presented his compromise plan. Asking for two hours of reflection, the panel debated, the proposal, with Louis Pettiti of France and Andres Aguilar of Venezuela dissenting.

After Mohamed Bedjaoui of Algeria and Adib Daoudi of Syria came down in favor of the plan and Harry Jayewardene of Sri Lanka remained undecided, the group telephoned U.N. headquarters in New York to ask for Waldheim's advice, sources said.

Waldheim's office in turn telephoned the White House, the sources said. In the final hour before the negotiations collapsed early yesterday, Waldheim and Jordan telephoned the members trying to win over Aguilar and Pettiti.

But the two members refused to budge, brushing aside objections that they were obligated to go along with compromises accepted by Iran and the United States, according to sources.

Aguilar and Pettiti denied in telephone interviews yesterday that they spoke to any U.S. official during the commission's visit to Tehran.

Commission sources stressed that the decision to leave Tehran and decline Ghotbzadeh's final offer was made unanimously by the five commissioners with concurrence of Waldheim, who was consulting them by telephone early yesterday morning.

White House press secretary Jody Powell denied that Jordan played any role in the Suite 1001 discussions, saying "that was never the state of play." r

The final desperate attempt by Ghotbzadeh to keep the commission in Tehran -- including a promise to transfer the hostages to government control in two weeks -- was discounted by weary commissioners who had experienced a long succession of broken promises.

But sources close to Bani-Sadr and Ghotzadeh said the plan may have had a chance of working, taking into account reports of President Carter's recent willingness to make some expression of concern about developments that have marked its relations with Iran.

The five commissioners are scheduled to meet with Waldheim in New York this afternoon to discuss the next step in the complex mediation effort that the U.N. chief emphasized has been "suspended but not terminated."

In a telephone interview, Pettiti said the commission was caught off guard by Khomeini's statement setting new conditions for a hostage visit that were unacceptable to the commissioners who had been waiting for days to see the Americans.

Khomeini said Monday that the panel could interrogate an unspecified number of hostages accused of spying on Iran and could see all the hostages only after issuing a report outlining "crimes" of the deposed shah and alleged American perfidy in supproting him.

Waldheim, stressing that Iranian officials had promised in writing that the commission would see all the hostages, said in yesterday's interview that he had assumed that the government officials would clear the way for the visits with Khomeini and the militants.

"We negotiated with the government," he said, "and our interpretation was that the government would discuss this with the other power elements of the country -- Khomeini and the [militants]. What exactly happened, I can't tell you."

It was "quite impossible and an illusion" to get assurances from Khomeini before the panel arrived in Tehran, the U.N. chief said, responding to crticism that he should not have dispatched the commission before nailing down an agreement on the visits.