Three American churchmen and a French-born Algerian cardinal endorsed by Iran's militant Islamic students held midnight Christmas services for hostages in the occupied U.S. Embassy here and spent most of the night with the captive Americans.

The four clerics had the closest and longest independent look at the hostages since the Islamic students stormed the embassy Nov. 4, and took the Americans captive to press for the return of the deposed shah to face punishment for what the students say are his crimes against the Iranian people.

The clergymen said the hostages they saw -- in three separate groups -- appreared to be in good general condition. But, when they returned from the embassy early today, they declined to specify how many of the 50 hostages they actually saw or to provide details on the physical and psychological state after 50 days in the hands of their extremist Islamic captors. Reporters were not allowed inside.

The rev. William Sloane Coffin of Riverside Church in New York, one of the visitors, said the four churchmen saw the hostages separately in three groups and thus had to compare notes before arriving at a total of how many were seen overall.

A press aide for the group, Warren Day, said the clerics plan to make a complete report later today, after rest and discussion.

Coffin -- along with the Rev. William Howard, president of the National Council of Churches; Auxiliary Bishop Thomas Gumbleton of Detroit and Cardinal Leon-Etienne Duval, archbishop of Algiers -- spent about five hours in the occupied embassy, from 11 p.m. yesterday until 4 a.m. today.

Their description of the visit, sketchy though it was, indicated that the Iranian students tightly controlled contacts with the hostages. The clerics had planned a joint ecumenical Christmas service with all the hostages together, but apparently were barred from carrying it out.

Even under these circumstances, however, the visit seemed likely to give the hostages a psychological boost after seven weeks of stress in the hands of the student revolutionaries. Day said before the American churchmen left the United States that they had been bombarded with telephone calls from families and friends of the hostages eager to pass along messages and seek information on the condition of their loved ones.

The Christmas visit marked the first known close-up contact with the hostages by independent observers since Rep. George Hansen (R-Idaho) visited fewer than 20 of them about a month ago.

[An Idaho newspaper reported that Hansen has left for a return trip to Iran. In a between-planes telephone call to the Idaho Statesman, however, Hansen said it was not definite that he would go all the way to Tehran.]

U.S. officials in Washington have voiced considerable concern about the hostages' condition, citing reports that their hands remain loosely bound all the time and that diplomats suspected of spying have been interrogated repeatedly by their student captors.

Iranian authorities have responded that all 50 remaining captives are in good health and have the services of an Iranian Doctor regularly. But the students have refused U.S. demands for an independent team including a medical doctor to visit the embassy.

The agreement to allow last night's Christmas Eve visit was itself viewed as a significant concession, compared to the students' generally unbudging attitude. Despite increasing pressure even in Tehran for release of at least of at least some hostages, the students have insisted that only the return of the deposed shah will induce them to release their captives.

Even as the clergymen entered the embassy in Tehran's cold, clear Christmas Eve, Youthful protesters gathered before the embassy's main gate as they do every evening to shout anti-American slogans.

"Carter fascist, Carter fascist," they chanted. Or: "CIA, down with you, CIA, down with you."

Photographs of four hostages sitting, standing and lying down with Christmas cards at their feet were pasted on to a large poster and placed at the embassy entrance. While the services were going on inside, a truck filled with dozens of bags of Christmas cards pulled up at the gate, then swung around to a side entrance to make a late delivery. Foreign Minister Sadegh Ghotbzadeh wanted the students to beware of packages containing bombs, but no explosives were found.

More than half a million cards signed by several million Americans have gone into the embassy for the hostages, along with Christmas packages and gifts sent from the United States or provided by Christians from European embassies or local churches.

These concessions to the spirit of Christmas -- in the tension of an occupied embassy with hostages held by armed guards -- seemed calculated by the studnets to dispel some of the ugly image their actions have created in the United States and elsewhere for Iran's Islam-based revolution.

They were made despite ignorance of, and even disdian for, Christmas beliefs. One student spokesman, asked yesterday what time the services were planned, himself asked an enquiring reporter what time such services usually are held. Another, asked about the possibility of a release of hostages at Christmas time, replied: "Christmas? What is Christmas? We don't know about Christmas."

The clergymen's visit appeared to be the result of several simultaneous series of contacts with Iranian officials. Final permission for the three Americans to enter the embassy, however, was arranged in negotiations with the students late last week by two University of Kansas professors, Norman Forer and Clarence Dillingham.

Cardinal Duval, a 76-year-old French-born prelate, is known as a champion of liberal causes and was thought to appeal to the Iranian students because of his declarations in favor of Third World interests. In addition, his diocese of Algiers is the capital of the predominantly Moslem North African state of Algeria.

Coffin said before entering the embassy that his stay in Tehran is "open ended." He made it clear he is eager to broaden the scope of his visit to include an effort to free the hostages if the student militants give him a chance.

At the same time, he refused to comment on his feelings about the hostages or the actions of their student captors, expressing fear that this could damage his relations with the students. "I just think the hostages deserve Christmas services," he said.

This also was believed to have played a role in the clergymen's decision to refrain from discussing their visit to the embassy without first agreeing on how much they together had seen and how much they should reveal about it. For despite their general report that the hostages they saw were in good condition, many questions remained.

Among them:

Are all the hostages still in the embassy?

Have they been physically abused?

Are they still bound?

Has the prolonged captivity produced psycological problems?

Have any prisoners cooperated with the students trying to build espionage cases against some of the imprisoned U.S. Diplomats?

In other developments, Ghotbzadeh formally requested President Aristides Royo of Panama to extradite the deposed shah to pay for what the foreign minister called crimes on an "international scale."

"Iranians are in no doubt that -- despite frequent pressure by the United States -- the Panamanians and their government will not tolerate the presence of the shah in Panama," Ghotdzadeh said in a letter to Royo broadcast on the official state radio.

In addition to the three churchmen accepted by the students, eight U.S. Christian ministers and a Jewish rabbi from Mexico City arrived in Tehran in an effort to see the hostages and offer their services for religious ceremonies.

But they were given little chance of gaining entrance to the well-guarded embassy. The students stressed that only the clerics endorsed by them in earlier negotiations would be allowed access to the hostages.

Khomeini, meanwhile, urged Americans in a message broadcast by the state radio "for the sake of God and the commandments of Jesus Christ, ring the bells of your churches just once in support of the oppressed in Iran and in condemnation of oppressors."

The official Soviet news agency Tass quoted unidentified "observers" as saying U.S. Propsals for U.N. economic sanctions against Iran are an effort to draw other countries into America's problems. The Tass report stoped short of predicting a Soviet veto on sanctions when U.S. proposal is introduced to the United Nations.