The effort to transfer the estimated 50 Americans held hostage by Islamic militants to Iranian government control collasped in disarray Thursday night when a divided Revoluntionary Council failed to reach any decision.

The failure dashed rising hopes earlier Thursday of rapidly removing the hostages from the control of the captors, who have held them since seizing the U.S. Embassy Nov. 4.

Officially, Foreign Minister Sadegh Ghotbzadeh, who only hours earlier had said Iran was satisfied with the conciliatory U.S. guarantees involving the transfer, told reporters Thursday night that the council felt "they are not enough and we are seeking more clarification."

But a Revolutionary Council insider insisted after the four-hour session that in fact the American assurances were a "great success for Iran" and were invoked Thursday night merely as a pretext to mask the council's own deep decision.

Indicative of those splits was the absence of three clerical members -- Ayatollah Moussavi Ardabili, Hojatoleslam Javad Bahonar and Ayatollah Mohammed Beheshti -- from the session.

Moreover, another council member, Ayatollah Mohammed Reza Madavi Khani, abruptly denied an interview in the afternoon newspaper Kayhan in which he was quoted as predicting the hostages would be handed over Saturday to government authority.

That made it clear that the official optimism in Washington and Tehran had turned out to be no more justified than in two preceding failures to transfer the hostages over the past month.

More clearly than ever before, the fate of the hostages emerged not just as an American-Iranian issue, but as the key element in a power struggle between an increasingly beleaguered President Abol Hassan Bani-Sadr and the clerical right-wingers who control the students.

Insiders said the lineup in the inconclusive discussion Thursday night was eight favoring the transfer and two against. Nevertheless, maintaining the unanimity reached on Sunday of all 13 members was considered necessary for the plan to be carried out.

Even then, Bani-Sadr indicated continuing concern with the position of the nation's revolutionary leader, Ayatollah Ruhollah Khomeini. In an otherwise optimistic interview with the three American television networks Thursday morning, he cautioned that "you always need [Khomeini's] approval."

Some or all the council members are still expected to see Khomeini on Friday, but even Ghotbzadeh, the driving force behind the transfer, told reporters that the next chance for a Revolutionary Council meeting was "probably Sunday."

The wrangling council members Thursday night never even got down to discussing the details of the tranfer, which had been expected to be their principal task.

"They think by keeping the hostages they've got that much out of the United States," a council insider confided. He was alluding to President Carter's reported willingness in return for the transfer to eschew economic and political sanctions and public pressures to free the detained Americans until the new parliament is operational here in two months at the very earliest.

"They do not have enough courage," the insider said, suggesting that the council lacked the political will to find a way out of the crisis.

Revolutionary Council spokesman Hassan Habibi was apparently so embarassed by the meeting that he ducked out a back door, leaving Ghotbzadeh alone to face the press and explain the wreckage of his controversial initiative.

So confident were the militants holding the hostages of their clerical support that they telephoned Reuter news agency 15 minutes before Ghotbzadeh emerged to meet reporters. They had full details of the meeting.

Throughout the day they had opposed the hostage transfer, but said they would hand over their prisoners if the Revolutionary Council so ordered. t

Thursday night the militants insisted that "Carter should make an official statement." That appeared to repeat Bani-Sadr's statement Tuesday that the transfer depended on a public statement by the United States agreeing to Iran's conditions.

Oddly, Bani-Sadr's own public relations advisor, Ali Moussabi Garamudi, repeated that demand early Thursday afternoon, soon after Bani-Sadr himself had told CBS that "as far as I'm concerned, The United States has met the conditions."

Ever cautious, despite his desire to end the hostage crisis and push ahead with radical economic and social revisions, Bani-Sadr had added "but, of course, it [the transfer plan] has to be approved by the Revolutionary Council." The American assurances on that score -- contained in a note delivered Wednesday through the Swiss Embassy here -- sidestepped the public aspect of those commitments to avoid humiliating the Carter administration.

In retrospect, the unanimous Revolutionary Council vote Sunday, according to veteran diplomats here, appeared based on the supposition that the United States would never accept Iran's tough demands and call off new threatened economic and political actions.

If nothing else, the past week has given the White House an opportunity to argue that it has pursued every imaginable approach to reach a settlement with Iran.

But Khomeini had tipped his hand once again Tuesday in a statement preceding Bani-Sadr's offer designed to stave off the threatened sanctions. The 79-year-old leader in effect ruled out what he disparagingly called an "honorable settlement" of the crisis with the United States.

The next Iranian effort on the hostage issue is likely to be a revised version of the Nuremberg-war crimes trials to judge deposed shah Mohammad Reza Pahlavi's alleged misdeeds, much as the Allies judged the Nazi leaders after World War II.

The Revolutionary Council Sunday night approved the new plan. Its author, Lenin and Nobel Peace prizes winner Sean MacBride, had dropped his previous insistence that all the hostages be released before, or at the same time as, a United Nations commission starts operations.