The recent anti-American campaign here has helped produce a breakthrough in the long stymied negotiations between Iranian revolutionary authorities and Kurdish rebels pressing for constitutional guarantees of autonomy for their western province.

Following the student takeover of the U.S. Embassy in Tehran and the capture of Amiercan hostages, Iran's revoltuionary leader Ayatollah Ruhollah Khomeni has invoked the need for national unity against the United States. This nationalism has allowed him to drop, with minimum of public embarrassment, his call last summer to crush the Kurds which has proved militarily unattainable.

There are fears that autonomy for Iran's nearly 4 million Kurds could destabilize much of the Middle East since large Kurdish populations live in neighboring Iraq, Turkey and the Soviet Union, as well as a smaller concentration in Syria. Iranians also fear that autonomy for the Kurds would have a disruptive impact on Iran's other minorities, which also seek autonomy.

Khomeini has called for continued negotiations in an uncharacteristically conciliatory message to the Kurds Refering to his age and precarious health, 'khomeini, 79, said he was "expressing my humble desire as a servitor of the nation who is passing his last days of life.'

Only three months ago he singled out the Kurds for rebuke much as he does the United States today.

Similarly, the anti-American fervor sweeping Iran has served as a convenient vehicle for extreem leftist Kurdish groups to accept a silent partner status in a new round of negotiations underway with a government goodwill mission.

Previously, the Marxist-Leninist Fedayeen guerrillas and the Revolutinary Organization of Toilers of Kurdistan, or Komala, were considered to be determined to continue fighting, even if the majority Kurdish Democratic Party struck a deal with government negotiators.

An overall agreement still appears far away, according to analysts, despite cautious optimisn in Kurdistan sparked off by Khomeini's message.

The Kurds are demanding that autonomy be guaranteed in Iran's Islamic constitution, which is tentatively scheduled for referendum approval in little more than two weeks.

The constitution makes no provision for any deviation from a highly centralized state. This stand reflects a long-held Persian fear that autonomy for Kurdistan could prompt similar demands from oil rich Khuzestan, Baluchistan, the Turkomans and Azerbaijan, which account for roughtly half of Iran's population.

In the negotiations in Mahabad, the capital of an ill-fated Soviet-backed Kurdish republic in 1946, 1dariush Foruhar, the top government delegate, and Kurdish Democratic Party leader Abder Rahman Qassemlou have stressed that their first task is consolidating a still precarious week-old cease-fire and turning it into a binding armistice.

"We appreciate" Khomeini's Goodwill," Qassemlou said, but hope his representatives show a "willingness" to translate them into reality.

Although both Revolutionary Guards and Army troops have pulled back from the major Kurdish towns, the Kurds want the Revolutionary Guards withdrawn from the province entirely.

The Kurds also want to "freeze" both the numbers of Army troops in Kurdistan and their freedom of movement within it.

Yet a third problem involves smoothing out problems among the rival Kurdish groups. Long considered "American agents" by the revolutionaries because of their uncompromising refusal to stop fighting, the Fedayeen and Komala now have agreed to allow Sheik Ezzedine Hosseini to represent them during the negotiations.

The sheik is considered an acceptable spokesman for all Kurdish factions. They presumably would work out their tactics privately before meeting Qassemlou and the government negotiators.

Hossini has agreed to participate in the talks after Khomeini's meggage indirectly met his demands for a formal apology.

During the summer, Khomeini condemned both the sheik and Qassemlou calling them "corrupt of the earth." Khomeini refused any further dealings with them and tried to crush the Kurds.

But the Revolutionary Guards' poor showing and the Army's equally lackluster performance against the Kurds' forced Khomeini to yield.

Only after the military aspects of the problem are settled will the negotiators tackle the heart of the autonomy question, according to Qassemlou who returned to Mahabad Sunday after hiding three months in the mountains.

The government's present proposal offers the Kurds control of all economic, political, social and cultural assepects of their province. National defense, foreign policy, monetary matters and long-term economic planning remain a central government prerogative.

That proposal will be measured against a Kurdish draft, which has yet to be completed apparently because of differences among the various Kurdish groups.

Foruhar has asked already for postponement of the national constitutional referendum planned for early December, seemingly acknowledging that it would be hard to conclude the negotiations by then.

Among those preaching moderation to the Kurdish Democratic Party is a delagation of the Tude h or pro-Moscow communist party. Cynics, noting Tudeh's support for Khomeini, are convinced its tactics are motivated by a desire to advoid any pretex for increasing the armed forces.

Still in a shambles after the February revolution, that overthrew Shah Mohammad Reza Aphlavi, the armed forces suffer from a depleted officer corps, masive desertions, poor maintance of equipment and spare parts shortages.

Failure of the current talks might prompt Terhan to launch a massive build-up of the military to crush the Kurds. That would mean that Tudeh would face a strong military machine at a time the left is said to be making hearway in infiltrating key positions in the revlutionary government.