Top-ranking Iranian and U.S. officials said yesterday that the United States has accepted "in principle" Iran's four conditions for release of the 52 American hostages, and sources confirmed that, in effect, the two countries have begun a process of indirect bargaining about implementation of the terms.

In Tehran, Iranian Prime Minister Mohammed Ali Rajai told a news conference that Iran would seek some clarifications of the U.S. response to the conditions, which has been under study within his government since Nov. 12. The American document, according to sources, describes in detail what the U.S. government can do -- and in some cases cannot do -- to implement the four Iranian conditions that were first enunciated Sept. 12 by Ayatollah Ruhollah Khomeini.

Rajai also raised the possibility that more information will be provided to Washington on just what the Iranian government is seeking before it turns the hostages loose. He said, "America pretends that it has not understood the issue quite well. We are ready to give more explanation."

Rajai's remarks were the first public declaration that Iran was prepared to bargain over implementation of the four conditions. Earlier this week, The Washington Post reported that the small group in the prime minister's office handling the hostage issue was seeking additional information about the U.S. response.

The Iranian prime minister described as correct a statement made Wednesday in Algiers by Hojatoleslam Ali Akbar Hashemi Rafsanjani, Iran's parliamentary speaker, that the United States had agreed in principle to the Iranian conditions.

In Washington, Secretary of State Edmund Muskie responded to reports of Rajai's remarks by saying, "We have said publicly that we accepted the four points in principle. But that doesn't tell you much about the details, does it?"

Although no timetable was mentioned by sources in either Washington or Tehran, Rajai implied that he did not want the process to drag on.

The Iranian reply to the U.S. response, he said, was "being prepared." It apparently will be given to the Algerian diplomats now in Tehran for transmission to the United States.

Rajai said, "We hope the American government . . . does not try to mix in political discussions and carry on protracted talks."

The conditions, approved Nov. 2 by Iran's parliament, called on the United States to pledge not to interfere with Iranian internal affairs, to release the more than $8 billion in blocked Iranian assets in the United States, remove any legal claims filed against Iran in U.S. courts by individuals and corporations and send to Iran the wealth of the late shah and his family.

Rajai said Iran wants more information about actions the United States is prepared to take to send to Iran the late shah's wealth. He did not, however, rule out questioning other portions of the U.S. response.

Since that complex document was delivered in Tehran Nov. 12, officials in Washington have been awaiting some direct public word on how it was being received.

Yesterday, Rajai's statements were being interpreted at the State Department as a hopeful sign that the Iranian government finally had firmed up its own position and that, through the prime minister's office, an open dialogue, using intermediaries if necessary, could finally begin.

There were still conflicts in public positions taken by Iranian politicians, indicating that the political conflict within the Tehran government still goes on. Rajai, for example, was quoted as telling reporters that the frozen military spare parts and equipment represented an "important problem" and "the delivery of those arms is our right."

Rafsanjani has been quoted as saying that Iran would not accept delivery of arms from the United States.

Rajai, according to news reports, said the still-secret U.S. response is 40 pages long with additional explanatory material. Washington sources describe it as four or five pages long with appendices.

As for the hostages, Rajai said his government was "in the process" of taking over custody from the militant students who seized them at the U.S. embassy on Nov. 4, 1979.

Rafsanjani said in Algiers Wednesday that the hostages' eventual release would take place in Tehran and that the Algerians would take charge of their departure from Iran.

To illustrate the process of indirect bargaining, sources in touch with both capitals said yesterday the Iranians were dissatisfied with the U.S. response on the question of sending the shah's assets to Iran.

The Iranians, in their conditions, wanted President Carter by edict to take control of the assets of the shah and his family and order their transfer to the Tehran government. In private conversations, Tehran sources said what was really sought was U.S. legal recognition that Iran had nationalized the shah's family wealth, a step that would be considered to be effective within the United States.

Lawyers had told the Iranians of a case years ago where the assets of the king of Iraq had been nationalized by that country's revolutionary regime. But when the new Iraqi government tried to seize a bank account in New York belonging to the former Iraqi monarch, the courts turned it down on the ground that the U.S. government had not recognized the act of nationalization.

In its response to the Iranian condition, the Americans reportedly avoided any legal steps of the type sought by the Tehran government. Along with pledging assistance to Iran in using U.S. courts to press claims against the shah's money, the U.S. response promised aid in locating the assets. One possible way would be a demand by Washington that U.S. banks and other institutions report on any holdings they have that are owned by the former shah.

Unhappy with that approach, the Iranians now may ask Carter to freeze the shah family assets, much as he froze the Iranian government assets. Then with the assets held wherever they are, the Iranians would accept the U.S. idea of a "census," the official reporting of which U.S. institution holds what shah asset.

That idea, Washington sources said yesterday, would also pose legal problems, but would be explored in the course of exchanging approaches to come up with a solution that meets the needs of both countries.

Sources said yesterday that the two sides will have to work out the details on how the more than $8 billion in frozen Iranian assets will be released.

At the same time, some solution must be reached on dealing with the roughly 300 lawsuits that have been filed seeking money from the Iranian government for claims, since these legal actions could prevent most of the frozen funds from being returned to Tehran.