Twenty-eight people were killed today in fierce fighting between rival Moslem sects in the southern port city of Badar Lengeh, while in the northern city of Tabriz, clashes resumed between followers of Ayatollah Ruhollah Khomeini and his most powerful rival religious leader.

In all more than 200 people were wounded in the increasingly bitter conflicts developing in Iran's provinces.

In an effort to generate a massive public display of support for Khomeini's leadership. Iran's Revolutionary Council declared today a national holdiay. l

At least 300,000 demonstrators -- the largest crowd since the holy day of Ashura in November -- gathered at the occupied U.S. Embassy in Tehran. Tens of thousands more traveled to the holy city of Qom to demonstrate their backing for Khomeini.

Foreign Minister Sadegh Ghotbzadeh, meanwhile, appealed to Khomeini to resolve the latest hostage issue, forwarding to the 79-year-old revolutionary hero a new demand by the radical captors of the U.S. Embassy to hand over America's Charge d'Affaires Bruce Laingen for questioning about alleged espionage documents.

Khomeini gave no immediate response to the demand. But a spokesman for the hostages' keepers said they will abide by his decision on Laingen, the to U.S. official in Iran who has been forced into protective custody at the Foreign Ministry in Tehran since the embassy was seized Nov. 4.

In an attempt to ease the rising level of violence between Turkish-speaking Iranian followers of Khomeini's rival, Ayatollah Kazem Shariatmadari, and Khomeini loyalists in Azerbaijan Province, Iran's state radio broadcast a statement allegedly by shariatmadari disassociating himself from his supporters in the Moslem Peoples' Republican Party.

In the broadcast, Shariatmadari allegedly called upon his partisans to stay calm and avoid "the deepening of differnce."

Although one spokesman from Shariatmadari's home confirmed the statement by telephone, other colleagues in Qom said they knew nothing about it. In Tabriz, members of the political party claimed the statement was a fabrication and declared that their leader was being held under house arrest.

During today's demonstrations' in Qom, Khomeini's guards surrounded Shariatmadari's home and reportedly beat up his followers as they left his house, which is just 500 yards from Khomeini's headquarters.

Supporters of Shariatmadari fought Khomeini loyalists in the small, dusty city of Qom Friday, injuring at least 10 people.

Shariatmadari, who was born in the northwest province of East Azerbaijan and lives in the holy city with other national religious leaders, has openly disagreed with Khomeini on sections of the newly enacted constitution that gives Khomeini supreme power and provides little autonomy for Iran's provinces.

Shariatmadari's recommendation early last month to boycott the constitutional referendum has sparked weeks of sporadic fighting between his supporters in Azerbaijan and Khomeini's followers, setting the stage for a major showdown that could severely damage Khomeini because of the large number of Turkish-speaking Iranians throughout the country.

Regional uprisings among the Turkish-speaking Azerbaijanis, the Baluchis in the southeast, the Kurds in the west and the ethnic Arabs in the south have become heavy burden for Khomeini, reportedly distracting him from the fate of the American hostages who have spent almost nine weeks in captivity.

On this day of continued regional challenges to Khomeini's rule, Foreign Minister Ghotbzadeh moved to dispel any doubt about the religious figure's power. In an interview, he denied a recent CBS News report from Washington in which he was quoted as saying that Khomeini is cut off from information needed to run Iran.

"This is totally false, a total fabrication," the foreign minister said in an interview with NBC News. "The fact is Ayatollah Khomeini is getting the reports daily and full consultation on what's happening and he knows the situation perfectly well."

In the past several days, Khomeini has avoided statements involving the American captives and refused to meet with U.N. Secretary General Kurt Waldheim, who visited here this week in an attempt to help gain release of the hostages.

Khomeini apparently has been forced to focus much of his energies on his country's persistent regional unrest.

In today's skirmishes, the most serious violence erupted in Bandar Lengeh, a southern port city on the Persian Gulf near the Strait of Hormuz, through which half of the world's oil exports pass.

Although initial state radio reports said the fighting broke out during a demonstration to protest yesterday's fighting in Qom, sources in the ethnic Arab region indicated the battle grew out of tension between members of the Sunni and Shiite sects of Islam.

After harsh words were exchanged yesterday between leaders of each group, the Sunnis marched on the local headquarters of the revolutionary militia men, a local security force organized by Khomeini and loyal to his Shiite-based government, according to sources.

Last night, supporters from both sects flocked into Bandar Lengeh and fighting began that resulted in the 28 deaths and more than 100 injuries, according to the state radio and local sources.

In the northwest city of Tabriz, the stronghold of Shariatmadari, more than 100 persons were wounded in intense street fighting by large crowds armed with knives, bricks and wooden staves.

Today's confrontation between the rival ayatollahs' supporters continued fighting that began last night after word of the Qom clash traveled to the heart of Turkish-speaking Iran. Shariatmadari loyalists had seized the radio and television station, but lost it today to government forces.

Ayatollah Assadollah Madani, Khomeini's religious representative in Tabriz, reported that several cars had been set on fire and pictures of Khomeini ripped up as the factional fighting spread throughout the city.

The official Pars news agency reported last night that 400 Khomeini supporters took over the headquarters of the Moslem Peoples Republican Party, which was heavily fortified by Shariatmadari sympathizers just a week ago. At that time nine militiamen loyal to Khomeini were taken hostage for several days by Shariatmadari followers.

In another Pars report, 16 persons were wounded in the Azerbaijani city of Maragheh after Khomeini loyalists marched to protest the Qom fighting and confronted members of the Moslem Peoples Republican Party.