The Iranian radicals who have held an estimated 50 Americans hostage for four months abruptly agreed today to hand them over to the ruling Revoluntionary Council after losing a desperate final attempt to block a visit by a United Nations commission.

Informed sources here in the Iranian capital said the commission may visit the hostages within the next two to three days, and added that the Iranian armed forces are expected to take over informal guard of the Americans.

The bitter statement by the radicals, which reflected their more significant loss in an ongoing power struggle with President Abol Hassan Bani-Sadr and others working for a release of the hostages, was read on Tehran radio this afternoon.The students said their responsiblity for the hostages was "finished."

The 13-member Revolutionary Council met tonight and said it would accept responsibility for the hostages, who continue to be held by the Islamic theolgical students who seized the U.S. Embassy on Nov. 4. A bare majority of the council is believed to favor ending the U.S.-Iranian crisis.

Foreign Minister Sadegh Ghotbzadeh, who has played a leading role in the crisis, said a government commission will be formed Friday to decide how the hostages will be turned over to government control.

Emerging from the Revolutionary Council's meeting, Ghotbzadeh cautioned reporters against assuming that today's decision meant that the actual release of the captives was imminent.

"You are jumping too far ahead," he said, reiterating that Iran still expects the United States to meet previously

In another development the Iranian government today authorized this reporter and Newsweek correspondent to reenter Iran and resume work. All American correspondents were ordered to leave Iran on Jan. 14. It was not immediately clear when other U.S. journalists will be readmitted.

The radicals' statement sharply attacked the five-member fact-finding team sent here by the United Nations. The commission was "ordered by America and meeting [with the hostages] is really what the American government wants," the state said.

"But what could we do when the people who are responsible for the commission have accepted that the commission is allowed to do every thing it wants?" the radicals asked.

In recognizing that "our responsiblity with regard to hostages" is finished, the students tacitly dropped their hard-line demand that the detained Americans would only be released in exchange for the return of the deposed shah, Mohammad Reza Pahlavi, from his exile in Panama.

Underlining what their spokesman called "intolerable government pressures," the student statement said that "to allay any misunderstanding" the Revolutionary Council should "take the hostages -- that is, the American spies -- from us and deal with them as it deems appropriate" since "we cannot bow to a view we do not accept."

Student spokesmen tonight said they considered the embassy their "home" and "we're not going to leave." Informed sources said the statement may indicate that the students are prepared to let the hostages leave the embassy in the custody of Iranian troops, a move that would ease the efforts for release.

"Our statement is not related to any order" by Khomeini, the students claimed. "It is entirely the decision of the students."

Informed sources insisted, however, that the students had been rebuffed Wednesday night by Khomeini in a desperate final effort to maintain their authority against Bani-Sadr and the Revolutionary Council in the argument over the U.N. commission, which arrived here 12 days ago.

With Secrecy shrouding the wheeling and dealing that involves both domestic Iranian politics and international diplomatic exchanges with Panama, United States and U.N. Secretary General Kurt Waldheim, the commission had decided to leave this morning without seeing the hostages.

The commission had sent the pilot of its executive jet to the airport to prepare a plan for the return flight to Geneva and had all but accepted the failure of its present mission, retaining only a faint hope of returning later to Tehran to see the hostages.

Calling the radicals' move a disguised capitulation, informed sources said the action had helped "gain two weeks."

They explained that the methods for freeing the hostages could be worked out now before the parliamentary elections at the end of this month, enabling the newly formed legislature to tackle the question as one of its first orders of business when it meets in early April.

On Feb. 24, Khomeini announced that the new parliament would be entrusted with settling the hostage problem, his way of saying that the American hostages would not be released before then.

The dramatic radio announcement climaxed a bitter behind-the-scenes power struggle. Wednesday night, the students either saw -- or sought to see -- Khomeini, but in any case they failed to win his support for the rebuffing the U.N. commission's right to visit all the embassy hostages.

This morning Badi-Sadr saw Khomeini, and informed sources said he presented "serious reassurances" about the future steps to be taken in the crisis.

Although no details were immediately available, observers suggested that the reassurances dealt with:

A compromise on the nature of the visit to the hostages that would satisfy both Iranian desires to hear the detained Americans as witnesses and Washington's insistence that they basically be seen, but not heard, for fear of what they might say after so long an ordeal.

American worries about meeting Bani-Sadr's three conditions involving U.S. admission of guilt in past interference in Iranian domestic affairs; a promise not to do so in the future; and an engagement not to block the extradition of the deposed shah, from Panama or the return of his wealth.

The Iranian demand for the shah's extradition. In recent days lawyers working for Iran's case have insisted that Tehran had a good case on criminal charges against him, but formally must promise not to execute the shah since Panamanian law forbids extradition on political grounds or if the person risks losing his life upon being returned.

Informed sources said that Iranian doctors had visited the hostages and found "the majority" to be "in good health." They also said the commission could consult with the doctors if any further details were required.

The radicals have divided the hostages into three different groups, the sources said. The most cooperative are kept in a separate house on the 27-acre compound. The 14 accused of espionage are kept in the main embassy building basement and the remainder are exposed on the ground and frist floors.

Throughout much of the 12-day trial of strength that pitted the government and commission against the students, the militants wanted to limit visits to 30 hostages. Informed sources said that only 30 hostages were in the embassy at the time -- confirming reports that since as early as December the students had taken a number of hostages out of the embassy compound.

When a Revoluntionary Council member visited the embassy last Friday, however, he was able to talk to 44 of 45 hostages and see the rest, according to informed sources.

In dealing with the Revolutionary Council's demands to see the hostages, the students and their allies constantly sought to maneuver and delay even after Bani-Sadr, Ghotbzadeh and the majority of the Revolutionary Council had received Khomeini's passive support.

Analyzing the past week, informed sources said the real showdown began at the weekend when the Revolutionary Council decided that the commission should visit the hostages, but proved incapable of imposing its will.

Khomeini refused to issue the orders that the students have insisted were the only ones they would respect ever since they seized the embassy on Nov. 4.

With tension mounting daily, the students kept changing their demands. When Ghotbzadeh told the students last Monday that the commission had to see all the hostages, not just 30, the foreign minister threatened to denounce them in an open letter to Khomeini, and the ayatollah backed him up.

Then the students agreed to such a visit, but said that Khomeini had not fixed a date for it and thus the commission should go away, publish its report and eventually -- if it were judged to be favorable -- a visit could be arranged thereafter.

When the demand was rejected, the students then agreed to a visit, but only to the 14 hostages accused of espionage. The commission, the students insisted, could issue a report about their alleged espionage activities and then could see the remaining hostages at a later date.

At the weekly meeting of the Revolutatiionary Council with the government ministers Wednesday, a five-man delegation including Bani-Sadr and Ghotbzadeh met with the students. The students' demands were rejected and they were told the visit would go adhead since it was Khomeini's wish.

At the fateful meeting this morning with the commission at the Foreign Ministry, Ghotbzadeh in effect explained that the students would back down without being publicly humiliated to do so.