Four diplomats who visited Americans being held hostage by Iraian militants at the U.S. Embassy here told colleagues today that many of the hostages are kept bound and are being spoon-fed by their captors.

Meanwhile Ayatollah Ruhollah Khomeini, Iran's Moslem ruler, reportedly rejected a direct plea from Pope John Paul II to free the hostages.

In a meeting with a papal envoy in the Iranian holy city of Qom, Khomeini, according to the official Pars News Agency, said the problem was "in the hands of the nations." He added that "if Christ were here, he would censure [President] Carter" for refusing Iran's demand that Shah Mohammad Reza Pahlavi be sent back to Iran.

[As diplomatic maneuvers to resolve the week-old crisis continued, the Palestine Liberation Organization vowed to exert its "utmost efforts" to obtain the release of the American hostages. Details, Page A12.]

The envoys of Syria, Algeria, France and Sweden were the first outsiders allowed to view the hostages since Iranian militants took over the embassy Nov. 4.

After the diplomats emerged from the embassy, the Iranian occupiers distributed a petition, porportedly signed by about half the captives, appealing to the U.S. government to extradite the shah. The petition said that nothing less would win the hostages' freedom.

U.S. officials in Washington dismissed the petition, saying that even if authentic it was signed under "duress" and would play no role in U.S. decision-making.

The visiting diplomats reported that some of the hostages were kept bound with ropes, even when they slept, and had to be spoon-fed by their Iranian guards. Diplomatic sources who spoke to the four visitors said some of the captives had their feet bound, some their hands and others both hands and feet.

The Swedish and Syrian ambassadors and Algerian and French charges d'affaires were not allowed to sell all the hostages, the sources said, because the students invoked security reasons. The visitors saw only five of the seven women hostages. They were reported sitting in a row with their faces to the wall, apparently in silent protest against their captors since the other hostages were allowed to speak.

One of the two women hostages not seen today by the visitors is believed to be four months pregnant.

The description of the hostages' plight came to light amid the first visible diplomatic movement here in the crisis over the hostages. However, there were no further indications about an eventual resolution of the embassy takeover.

Initially the visitors offered only vague public accounts of the conditions inside the embassy, describing the Americans as "a bit tired" but without "major complications about their health." Later, however, they provided more details in private talks with other diplomats here.

In addition to authorizing the four diplomats to visit the embassy, the Iranians showed some new signs of possible flexibility:

Two Palestine Liberation Organization representatives, Abu Walid and Hanni Hassan, held "substantial" talks about the hostages this morning with Adol Hassan Bani-Sadr, the official newly in charge of the ruling Revolutionary Council's foreign affairs. Palestinian sources described the meeting as "exploratory." Bani-Sadr, who flew by helicopter to the holy city of Qom to report at midday at Ayatollah Khomeini, was to hold further talks with the Palestinians this evening.

Abu Walid, orginally scheduled to return to Beirut Sunday, was asked by Bani-Sadr to stay on for another day or two, according to the sources.

Diplomats of the 10 european Economic Community countries conferred with Bani-Sadr and sought assurances about the American hostages and protection of their own missions.

Bishop Annibale Bugnini, the papal nuncio, was received in Qom today to Khomeini to whom he gave a letter about the hostages from Pope John Paul II. The nuncio is to be allowed to visit the hostages, according to Tehran television news.

Although Iranian officials and the students who took over the embassy insist that no negotiations are possible and that the hostages will be released only when the shah is brought back here to stand trial, Bani-Sadr's hectic travels indicated some kind of compromise might be under consideration.

Only yesterday he had conferred with Khomeini in Qom and returned to Tehran late last night.

In a long Tehran radio message to the American people, Bani-Sadr basically asked them to bring pressure on their governments, whose successive administrations for more than a generation were accused of dominating Iran.

"Oh, Americans, they lie to you," he said of the Carter administration.

The deposed monarch was compared to Nazi war criminals brought to book after World War II at the Nuremberg trials and Bani-Sadr argued that the American people should "ask your government to sincerely abide by human rights and extradite the former shah."

The message was generally interpreted as an effort to persuade the United States to make a gesture toward Iran that could help release the hostages without necessarily handing over the shah.

The students produced photocopies of a list of 33 hostages who were said to have signed a petition asking for the shah's return here. Also displayed was a letter purportedly written by U.S. Marine Sgt. Kevin Hermening to his mother and stepfather in Oak Creek, Wis.

Both the explantory text accompanying the list and the letter, which mentioned being bound hand and foot, were so oddly couched in English as to suggest that the signatories were perhaps signaling that they had acted under duress.

The list of names, which included those of Michael Metrenko, head of the political section, and John Limbert, former consul in Shiraz, was preceded by the phrase, "We request from our nation to return shah to Iranian government. In this case we will be free." It ended, "the students asked of 35 hostages if they did want to sign the above questions. 33 of them signed it. Tomorrow we will asked of rest."

The Marine's letter, written in block letters, also failed to use the article in describing the shah, a common Iranian habit in their spoken English.

Sweden Ambassador Kaj Sundberg and the three other diplomatic vistors seemed visibly upset when a crowd of Iranian demonstrators jeered and jostled them as they entered the embassy compound.

Upon emerging after a 90-minute visit, Sundberg said that talking to the press "would not be useful at this point." He added that the group's public statement on the captives' condition "was agreed upon with our hosts."

As the statement between Washington and Tehran continued, Ramsey Clark and Senate intelligence aide William Miller were still waiting in Turkey for permission to visit Iran and try to negotiate the hostages' release. But a third member of the team, the head of the State Department's Iranian desk, Henry Precht, flew back to Washington, informed sources said.

In his reply to the papal envoy, Khomeini was quoted as saying he could not free the hostages because "the problem is not in my hands [but] in the hands of the nation."

According to Pars News Agency, the ayatollah told the envoy that the Americans in the embassy were "agents of intrigue and espionage.'"

Addressing himself to the pope, Khomeini added, "If Christ were here he would censure Carter. If Christ were here he would have rescued us from this enemy of the people and mankind. You are his representative. You must do as Christ would."

Khomeini also accused the Vatican of not being concerned about Iran "during the 50 years [when] 35 million Iranians have been under the yoke of imperialism, in particular America and lately Mr. Carter.""