The State Department yesterday labeled Iran's continuing refusal to clarify how many Americans are being held in the U.S. Embassy in Tehran "a very cruel numbers game."

Department spokesman Howard Leeb said reports by visiting American clergyman that they saw only 43 Americans in the embassy "underscore the need for a list of the hostages," something the Iranians holding them have refused to provide.

U.S. officials persistently have said there are 50 Americans in the embassy, according to their calculations, in addition to three others who are being held at the Iranian Foreign Ministry.

Since the takeover began on Nov. 4, Ayatollah Ruhollah Khomeini's government and the militant students occupying the embassy have rebuffed repeated appeals to provide an accounting of the captive Americans.

Yesterday's announcement by three American clergymen -- the Rev. William Sloane Coffin Jr., Rev. William Howard and Auxiliary Bishop Thomas J. Gumbleton -- that they saw only 43 hostages during their five-hour stay in the embassy only served to reopen the persistent questions about the numbers.

While the United States has consistently stuck to the figure of 50, officials have refused to give a list of names of those they believe to be captives. The closet the United States has come to giving an exact accounting came in documents presented to the World Court in support of the U.S. case against Iran. Those documents listed three categories of hostages:

Twenty-eight persons recognized as diplomats by Iran, including four consular officials.

Twenty administrative and technical staff members.

Two private U.S. citizens who were visiting the embassy at the time of the seizure.

In addition, three diplomats are being held at the Foreign Ministry.

Asked yesterday about the status of the Americans unaccounted for by the clergymen, a State Department official said, "At this stage we're just reluctant to make any assumptions."

Privately officials speculated that there were a number of possible explanations as to why the churchmen believe they saw only 43 hostages. These range from incorrect counts to the possibility that some of the hostages were ill or had been moved out of the 29-acre embassy compound.

"We're not saying anything until we have a chance to speak with the clergymen, and we haven't yet," said David Passage, a department spokesman.

There have been unconfirmed news reports that Secretary of State Cyrus Vance told the clergymen before their departure for Tehran that four of the hostages were believed to be suffering from nervous exhaustion and that two others suffered from high blood pressure and bone disease.

Adding to the general confusion over numbers are reports that the students in the embassy yesterday claimed variously that there were 50 hostages, 49 hostages; that the clergymen had seen all the hostages; and that perhaps they had not been allowed to see those the students say were spies.

When the radical students stormed the embassy 52 days ago, journalists quoted them as saying there were 63 American hostages in the compound. By Thanksgiving, a group of 13 blacks and women had been released leaving 50 hostages behind, by this count.

During this period it also emerged that three Americans, including Charge d'Affaires Bruce Laingen, were in the Foreign Ministry. At one point the three were said to be free to leave, but this was quickly countermanded by an assertion by the Iranians that it would not be "safe" for them to do so.

There have been several pledges or suggestions by Iranian officials that observers teams would be allowed to see all the hostages. The clergymen yesterday, however, were not allowed to see them all together, in apparent violation of what they believe they were promised.

On Dec. 16, during an appearance on ABC's "Issues and Answers", for example, Foreign Minister Sadegh Ghotbzadeh pledged, "You'll see them all" during Christmas services.

Yet, the clergymen did not see all the hostages, if the U.S. claim of 50 is correct and if the clergymen's own accounting is accurate.

Their experience is similar to those of previous outsiders who have been allowed into the embassy.

The first group to visit the embassy was a four-man diplomatic team led by Papal Nuncio Msgr. Annibale Bugnini, last Nov. 10. Bugnini's group was allowed to stroll briefly through the embassy but said they did not see all of the hostages.

Two weeks later, Rep. George V. Hansen (R-Idaho), during a controversial private visit to Tehran, was allowed to visit the embassy. Hansen said he saw fewer than 20 of the hostages, and said they appeared to be in sound physicial condition, but some were fatigued and appeared in need of bathing facilities.

Then, in early December, during their fifth week of captivity, the foreign minister, and the Revolutionary Guard commander. Abu Shaif, hinted that some of the hostages had been moved out of the embassy. At the time diplomatic sources in Tehran told Washington Post correspondent Jonathan Randal that as many as 22 of the hostages may have been taken from the compound.

Shortly afterward, however, Ghotbzadeh brushed away reporter's questions about the hostages, saying, "They are safe and sound. As for their geographic location, it's none of your business."

Days later two self-appointed negotiators -- University of Kansas professors Norman Forer and Clarence Dillingham, both long associated with anti-shah, demonstrations in the United States -- asked to meet with the captives.

Their request was denied on Dec. 8.

As Criticism of the Iranian position mounted, the militants again sought to deflect the charges against them.

On Dec. 10 NBC television broadcast a controversial interview with Marine Cpl. William Gallegos. Gallegos said he saw only 30 of the hostages, and could not account for the other 20.

Again, however, the numbers were not firm or verifiable.

In the weeks since the takeover began, U.S. intelligence analysts have been trying to piece together an assessment of the hostages conditions, analyzing film shown on Iranian television, and collecting shreds of information.

Yesterday, however, from their seventh-floor offices at the State Department building, a member of the Iranian Task Force would say only that "the discrepancies in the numbers continue."