Three American clergymen held Easter services for the hostages in the U.S. Embassy today as a self-appointed international commission launched a last-ditch effort to salvage a hostage transfer plan that would avert U.S. sanctions.

The clergymen, who oppose the holding of hostages but sympathize with the militant captors' aims, said the Americans were being treated well. They said they believed they had seen all the hostages, but could not specify how many they actually did see.

The Easter services and visit with the hostages coincided with a day of intense efforts to resurrect a plan to transfer the hostages from the hands of their militant student captors to government control.

But an ad hoc commission of five non-Iranian intermediaries in the hostage crisis was unable to present its proposals to Iran's ruling Revolutionary Council tonight, and commission members held out little hope that the transfer plan could be saved.

In a meeting tonight, the Revolutionary Council, which had been expected to announce a decision on the transfer plan, instead appointed a four-man delegation to call on Ayatollah Ruhollah Khomeini Monday morning and leave the final word up to him.

Foreign Minister Sadegh Ghotbzadeh said a decision had been reached but it would not be announced until Monday, after the visit to Khomeini. Others said, however, that the decision to send the delegation to Khomeini reflected continuing divisions within the ruling council.

Khomeini so far has said he would refer decisions on the hostages' fate to Iran's future parliament, but associates say he privately opposes a transfer of the hostages from the militants' control.

The scheduled meeting with Khomeini appeared to offer Iran its last chance to take action that would head off yet unspecified U.S. sanctions, informed souces here said.

U.S. officials tonight repeatedly sought more information about the developments here in telephone calls to mediators in the crisis, sources said.

The U.S. clergymen, the Revs. Jack Bremer of Lawrence, Kan., Darrell Rupiper of Omaha, and Nelson Thompson of Kansas City, Mo., spent 5 1/2 hours inside the occupied U.S. Embassy in what they called "a moving and draining" experience. Bremer and Thompson are Methodists and Rupiper is a Roman Catholic.

In a news conference in the embassy compound afterwards, the clergymen, members of the Committee for American-Iranian Crisis Resolution, based in Lawrence, said most of the hostages took part in the Easter services and that they then saw the captives in groups of twos, three and fours.

[The clergymen all had made prevous visits to Iran under the auspices of the committee and saw two of the hostages on their visit in February, Reuter reported.]

The militants restricted coverage of the news conference to selected reporters for the three U.S. television networks, but no American print journalists were admitted.

According to other journalists present at the news conference, the clergymen said they had not been able to put a precise figure on the number of hostages they saw because they had split up to conduct separate services and had not had time to compare notes.

Rupiper said they had no way of knowing whether they had seen all of the captives, but that the militants had assured them that all of them would be there and that he had no reason to believe that this was not the case. w

The ministers said they had passed letters to each of the captives from their families and would be taking the hostages' mail back to the United States.

Also appearing at the embassy today were Greek Catholic Archbishop Hilarion Capucci, Papal Nuncio Annibale Bugnini and two Iranians priests.

Capucci said the hostages told the clergyman their conditions were good. He added that the best proof of this was in "their faces, their smiles and their healthy figures."

The American clerics also said, in the presence of the Iranian captors, that the hostages were in good physical and mental health.

When asked later at the news conference whether they saw any hostages who were in poor mental or physical condition, both Thompson and Rupiper answered: "No."

"I saw no one who I would honestly judge had any nervous or phychological condition," Bremer added.

"It has been said again and again and again that the hostages are being well treated," Rupiper said. "Today we heard the same thing. They have excercise bicycles, Ping Pong, watch TV, see movies, video cassettes. The food is fine. They say that the students are treating them correctly."

Past visitors, however, have spoken of mental stress among some of the hostages, and television films last month showed that most in a group of 11 were pictured appeared to be listless and suffering some degree of depression. One, embassy press attache Barry Rosen, complained of heart trouble, nervousness and insomnia.

In the closest any of the U.S. clergymen came to criticizing the conditions of detention, Bremer remarked: "I do confirm from my own first-hand impression they were tired of being here and want to go home."

The clergymen mentioned only two of the hostages by name, Katherine Koob and Elizabeth Ann Swift, who were described as being in "exuberant spirits." The only women hostages remaining in the embassy, Koob and Swift also were said to be living "a very religious life together."

In addition to seeing hostages, Capucci and Bugnini also reportedly negotiated with the militant captors, as members of the self-appointed mediation commission. The panel was formed yesterday and gave itself 48 hours to find a compromise between Washington and Tehran that would enable negotiations to resolve the crisis.

They did not reveal the nature of their proposals.

The other members of the commission were Swiss Ambassador Erik Lang, French lawyer Christian Bourguet and Argentine attorney Hector Vilalon. The three had been key intermediaries in communications between U.S. and Iranian leaders in recent days.

Bourguet and Vilalon also were involved in Iran's effort to extradite the deposed shah, Mohammad Reza Pahlavi, from Panama before his departure for Egypt March 23.

Capucci has visisted Iran three times since the revolution and is believed to enjoy good relations with the embassy militants because of his support of Palestinian guerrillas.

Capucci was jailed by the Israelis several years ago after conviction on charges of smuggling guns to the Palestinian guerrillas. His role in the efforts to transfer the U.S. hostages here to the control of the Revolutionary Council remains unclear.

Bugnini, the pope's resident representative in Iran, was one of the first envoys to appeal directly to Khomeini for the hostages' release after they were seized five months ago. At the time, Khomeini rejected a papal message handed him by Bugnini, declared the hostages' fate was in the hands of the Iranian nation and said the world's Christians should condemn President Carter.

Commission sources outlined a series of events that gave rise to new optimism about a hostage transfer last week before leading to yet another impasse. The sources said Iran's Revolutionary Council unanimously approved a hostage transfer in a meeting a week ago Sunday, but when Khomeini failed to mention the proposed transfer in statements that week, council hard-liners organized new resistance to the plan.

Iranian President Abol Hassan Bani-Sadr and Ghotbzadeh want to end the hostage situation, but members of the clerical Islamic Republican Party oppose a transfer and apparently are using the issue to press their power struggle with Bani-Sadr.

Informed sources said only five of the Revolutionary Council's 13 members opposed the tranfer, but that this was enough to discourage Khomeini from approving it.

The council, which has been expected to reply to President Carter's latest remarks on the subject and definitively pass judgement on a transfer plan tonight, emerged from a meeting deeply divided.

The only decision made was that four council members -- Bani-Sadr, Ghotbzadeh, Oil Minister Ali Akbar Monifar and Ayatollah Madavi Kani -- would confer with Khomeini Monday and seek his judgment.

In another development, the Islamic Republican Party newspaper, Kayhan, renewed its attack on the hostages, quoting one of its members on the Revolutionary Council, Ayatollah yakbar Hashemi Rafsanjani, as saying, "The question of handing over the hostages to the Revolutionary Council is finished."