Militant Iranians occupying the U.S. Embassy here produced a purported secret State Department cable today that they said shows that two of the 50 hostages they are holding are Central Intelligence Agency officers serving under diplomatic cover.

In a news conference held in a courtyard at the embassy, the Iranians distributed copies of the document, apparently signed by charge d'affaires L. Bruce Laingen. The document accepts assignment of the two to the embassy.

One of the two individuals named, William Daugherty, has admitted he is a CIA employe, the Iranians said. The other name in the cable was Malcolm Kalp.

State Department spokesman David Passage refused to comment on the allegation that the two men were CIA agents. He said, however, that the Iranians occupying the embassy "have an ample record of forgery, misrepresentation and fabrication."

Passage added that "the matter of confessions should be viewed in the context of the circumstances in which the hostages are being held," noting that "they are into the 27th day under duress, in barbaric conditions."

The students insisted the alleged document was "only a single example" proving their case that the hostages were not "simple diplomats" protected by immunity, but spies who face trial unless Shah Mohammad Reza Pahlavi is returned to Iran.

More documents existed "about CIA involvement in our internal affairs," the students said, "and we will publish them when we feel it is necessary."

The alleged document, dated Aug. 9, approved assignment of Kalp and Daugherty. In it Laingen said they "must have" cover as second and third secretaries, because of the sensitivity of the situation.

Diplomats noted that governments routinely assign covers to intelligence operatives stationed to missions abroad to provide them with diplomatic immunity.

The students also said that Laingen, political officer Victor Tomseth and Col. Leland Holland, the embassy security chief, are now considered spies. They have been living in a wing of the Foreign Ministry since the seizure of the embassy.

"A lot of evidence has been found about the espionage of these people," a student spokesman told reporters as armed men looked on. "They, too, will be tried, like the rest" of the hostages.

Underlying their emergence as the seemingly paramount power in the country alongside Ayatollah Ruhollah Khomeini himself, the students contradicted new Foreign Minister Sadegh Ghotbzadeh who subsequently fell in with their hard line.

In a news conference yesterday, Ghotbzadeh had said that the three U.S. diplomats at the Foreign Ministry were not considered hostages, would not stand trial and were free to leave Iran although it was not safe at the moment for them to do so.

"If they want to leave I will try to facilitate things," he had said, although noting that "providing security from the Foreign Ministry to the airport at this time is rather difficult with the tension in the country."

Faced with serious student denunciations, Ghotbzadeh made a radio announcement just before the students' news conference today. He denied the the three Americans could leave Iran.

If Laingen "and his two colleagues leave the Foreign Ministry where they have taken refuge," Ghotbzadeh said, "the Foreign Ministry will not accept any responsibility."

Ghotbzadeh's predecessor, Abol Hassan Bani-Sadr, was meanwhile quoted as indirectly accusing Khomeini and Ghotbzadeh of having undermined efforts at negotiation.

"The point really is we adopted a policy that led to deadlock," Bani-Sadr was quoted as saying in an interview published by the afternoon Tehran newspaper Ettelaat.

Bani-Sadr, who was dismissed as acting foreign minister earlier this week but who retains his economic portfolio in the Islamic Revolutionary Council, was reported as saying that Ghotbzadeh had spread false propaganda and slandered the U.N. Security Council.

This and Khomeini's hard-line demand for the extradition of the shah in exchange for the hostages "is not something that would be fruitful," Bani-Sadr was quoted as saying.

Diplomats noted that Laingen, Tomseth and Holland have not sought refuge at the Foreign Ministry. Rather, the diplomats said, they were there to demand that the Iranian authorities provide the protection guaranteed foreign missions under international law and dislodge the students.

A student spokesman said Kalp had not yet been questioned about his alleged CIA connections.

Once again the students declined to fix a date for the threatened spy trials -- claiming the decision was "up to the people and Imam Khomeini."

But they hinted nothing would be announced until the shah physically left the United States for a third country.

"Letting the shah leave the United States is a bigger crime than admitting him in the first place," they said, developing the agrument that the United States was responsible for returning the deposed monarch to Iran to stand trial for his alleged misdeeds.

Apparently stung by complaints by President Carter and other American and foreign sources about the hostages' conditions of detention, the students said, "We assure the people of the world and the American people of (their) safety, health and comfort."

There have been charges that the hostages were kept bound, prevented from communicating with any of their colleagues except those in the same room, were unable to change their clothes and wash themselves adequately.

Newsmen's questions suggesting the press be allowed to verify the hostages' condition, however, were summarily dismissed by student spokesmen "for security reasons" which were never explained.

Asked about rumors that they had transferred hostages from the embassy, the students evaded the question. Instead they repeated their standard line that "the hostages are in our hands and we protect them strongly. We are ready so that in the case of any military intervention we will destroy them."

Ironically, the purported document said the assignment of Daugherty and Kalp meant starting "with a clean slate" in light of the "great sensitivity locally to any hint of CIA activity."

"It is of the highest importance that cover be the best we can come up with," the purported cable said. "Hence there is no question as to the need for second and third secretary titles for these two officers. We must have them."

The purported cable described Daugherty and Kalp's assignments as "SRF assignments" and said that the embassy would "hold to the present total of four SRF officer assignments for the forseeable future."

There is no indication what the letters SRF meant and one of the Iranians conducting the press conference suggested that the reporters "ask the CIA."

[Officials in Washington would not say what SRF stands for.]