Violent clashes broke out today between leftist students and right-wing Moslems at several Iranian colleges following the announcement of a government campaign to purge the higher education system as part of a "cultural resurgence."

At least one youth died when he was lynched by a mob at the Tehran Teachers Training College near the occupied U.S. Embassy, and hundreds of others were injured in fighting on several campuses, Iranian news media reported.

The fiercest fighting reportedly took place at Shiraz University in southern Iran, where about 300 persons were said to have been hurt.

In other developments around the country, three Jewish brothers were sentenced to death on espionage charges in the city of Hamadan, more fighting between government forces and rebellious Kurds was reported near Iran's border with Iraq and a Revolutionary Council member in Tehran announced another postponement of a parliamentary runoff election. [In Paris, Iranian Foreign Minister Sadegh Ghotbzadeh boarded a flight for Tehran at Orly Airport, news agencies reported. Ghotbzadeh told reporters his visit to France was of "purely personal nature." Iranian officials in Tehran had earlier denied that Ghotbzadeh had left Iran.]

A spokesman for President Abol Hassan Bani-Sadr denied that Iran's revolutionary leader, Ayatollah Ruhollah Khomeini, had told the ruling Revolutionary Council that the U.S. hostages would not be released before the U.S. presidential elections as asserted by President Carter. A spokesman at Khomeini's household in north Tehran also said that he knew nothing of any such remarks by the ayatollah.

[In an interview with the Harrisburg, Pa., Sunday Patriot News, Carter said he learned that the hostages might be held until after the election from diplomats who had "conversations with Khomeini's closest advisers."]

The campus clashes followed a Revolutionary Council decree Friday, with the blessing of Khomeini, that all political groups must move their offices off campus by Monday night or face their forced removal by the Iranian "masses."

Although no groups were specifically mentioned, the order apparently was directed at the leftist organizations that predominate at most universities. Opposing them has been the Moslem Students Following the Line of Imam, a fiercely pro-Khomeini group whose members are holding 50 American hostages at the U.S. Embassy here.

Allies of the group began a campaign to purge the universities of leftists and launch an Islamic "cultural revolution" when they took over and closed Tabriz University in that northwestern city last week. The movement then spread to other campuses around the country, including at least seven in the Tehran area.

Although the group's Moslem student followers appear to be in the minority on campuses here, they have the backing of many working-class Iranians, who seem to be joining their efforts to take control of the colleges.

Although its order was ostensibly impartial, the Revolutionary Council's leaning toward the Moslem students became apparent Friday when Hojatoleslam Mohammed Ali Khamenehi, a key Revolutionary Council member and leader of Tehran's mass Friday prayers, told a gathering at Tehran University: "You are right to get angry and sad seeing pictures of Lenin and red flags floating over our university, but don't worry. If it is necessary in the coming 48 hours, we will use the great force of the masses."

As he spoke, the crowd of more than 10,000 people chanted, "The universities must be made Islamic."

After a morning Revolutionary Council meeting today, Bani-Sadr said, "The university is a place for free debate, but not for setting up headquarters. We do not mean to promote one group and push another back."

Another aim of the council's order, Bani-Sadr said, was to create a "cultural resurgence." He said this was "part of a program to basically change Iran" and to achieve "cultural independence from foreign countries."

Following the college clashes, Revolutionary Council members and Interior Ministry supervisor Ayatollah Mahdavi Kani said that Revolutionary Guards and policemen had been ordered to keep the peace on the troubled campuses.

Kani also announced that the second round of the parliamentary elections, originally scheduled for April 3 and then postponed until May 2, have now been rescheduled for May 9 because of the May Day holiday. The delay in holding the parliamentary runoff has been a source of concern for Washington because Khomeini has entrusted the new assembly with deciding the fate of the U.S. hostages.

At Tehran University, Iran's largest, there were tense confrontations today between rival student groups, but no sign of serious violence.

At the technical faculty, one of a group of leftist students said that "reactionaries" Council and Bani-Sadr's government were "systematically organizing to crush the revolutionary movement in Iran." He said this was being opposed by such groups as the radical Islamic Mujaheddin-e-Khalq and the Marxist Fedayan guerrilla groups, the Socialist Workers Party, the Maoist Paykar organization and Kurdish guerrilla sympathizers.

In Hamadan, meanwhile, a revolutionary court sentenced to death three brothers of a Jewish family, two of them in abstentia, for allegedly cooperating with the Israeli intelligence service Mossad and the U.S. Central Intelligence Agency.

[In Washington, the State Department said that Bijan Ashtiani, an Iranian student who died in Lincoln, Neb., two weeks ago, was a victim of a heart attack and not violence as his father in Tehran had alleged, and that three Iranian physicians -- recommended by the Iranian Embassy -- signed an autopsy report.]