Casualties Are High as Kurds, Iraqis Clash : Unrest: Battles in the north leave up to 500 dead or wounded. The fighting is outside the zone being protected by allied forces.

Kurdish guerrillas and Saddam Hussein’s troops clashed in northern Iraq, leaving as many as 500 dead or wounded in what appeared to be the most serious fighting since Iraq crushed the Kurdish rebellion in March, U.N. officials said Friday.

The exact count of casualties was uncertain, but reports from the region reaching U.N. diplomats said Kurdish guerrillas, after two days of combat, had taken control of most of the northern Iraqi city of Sulaymaniyah. Smaller-scale fighting was reported in the city of Irbil.

A U.N. spokesman said that Prince Sadruddin Aga Khan, head of the U.N. humanitarian program in Iraq, had appealed to Iraqi authorities and Kurdish leaders to “use restraint on both sides,” and “received positive responses on both sides.”

According to a Reuters news agency report from northern Iraq, the Kurds and Iraqi officials agreed Friday to halt the fighting. The guerrillas claimed to have captured 2,500 Iraqis, including 70 officers, and to have destroyed six Iraqi tanks and seized 11. Diplomatic cables reaching U.N. headquarters in New York put the number of Iraqi prisoners at 1,000 and the number of tanks destroyed at 10.

In Washington, a U.S. military official said that allied troops were closely monitoring the situation, but the clashes had not spilled over into the Kurdish area of northern Iraq under allied protection.

U.S. and coalition forces were poised just over the border in Turkey to aid Kurds in the protected zone, but they had no orders to intervene in the fighting, the official said.

In Baghdad, Masoud Barzani, a Kurdish leader, said Friday that the fighting stemmed from a “misunderstanding” between Kurdish guerrillas and Iraqi soldiers. Iraq’s government issued a statement charging that the incident was caused by “infiltrators from Iran,” Iraq’s old war foe.

The widespread concern over the combat came as Iraq admitted that it has been engaged in a program to construct the world’s largest cannon, a “supergun” with the potential of firing nuclear, biological or chemical shells at targets 1,000 miles away, Western diplomats at the United Nations said.

Details of the program to build two superguns were disclosed in a document delivered to the U.N. special commission set up to find and eliminate all of Iraq’s weapons of mass destruction.

According to the document, Iraq possesses 44 pieces of steel tubing for the barrel of a 1,000-millimeter gun; the weapon’s steel base with 15 supports, plus four hydraulic shock absorbers for the gun. Such a weapon would have a muzzle diameter in excess of three feet--more than twice that of the 16-inch cannons on U.S. battleships.

Iraq also disclosed that it possesses a 350-millimeter cannon, the gun’s breech and 12 tons of gunpowder for that weapon. The document said the gunpowder was “usable” and that the cannon had been tested.

The latest disclosures, coupled with reports from U.N. nuclear inspectors last week that Iraq was building two huge production facilities to enrich uranium, has given the clearest indication of the massive scope of Hussein’s weapons development program. Portions of the enrichment plants were described as being on the scale of the U.S. Manhattan Project, which produced the atomic bomb at the close of World War II.

The existence of the supergun program had been suspected by allied intelligence for some time. In March, 1990, Gerald Vincent Bull, a Canadian and one of the world’s leading designers of artillery, was shot to death outside his home in suburban Brussels. Police said the killing was likely the work of professionals, and it was later revealed that Bull was the mastermind of the Iraqi cannon project, code-named “Project Babylon.”

Two weeks later, British customs agents seized eight steel tubes, each 1,000 millimeters in diameter, at the port of Teesport, destined for Iraq. Officials in Baghdad said they were petroleum pipes. The tubes were apparently manufactured innocently by a British concern, Sheffield Forgemasters. The firm had already shipped 44 steel tubes of the same diameter to Iraq.

In the latest document given to the United Nations, Iraq admitted possessing 44 steel tubes for the barrels of the 1,000-millimeter guns.

U.S. officials said the existence of Iraq’s supergun project was no surprise and that U.S. and allied intelligence agencies had intercepted critical components of the cannons before they reached Iraq.

Because the weapons were not complete, they were not targeted for destruction in allied air raids during the Persian Gulf War, a knowledgeable official said.

“They were in bits and pieces and weren’t worthy targets,” the official said. “And remember, they were part of a very complex shell game. A lot of stuff began to disperse before the air attacks.”

Disclosure of the superguns at the United Nations came as officials of the world organization in New York, Geneva and northern Iraq monitored the clash between the Kurds and Hussein’s forces.

Officials in New York said reports were being relayed by 87 U.N. guards in Sulaymaniyah. None of the guards were injured in the fighting. The officials described the fighting in Irbil as “minor.”

In Geneva, an aide to the U.N. high commissioner for refugees said the fighting started Wednesday during a demonstration in Irbil against high food prices. A U.S. military official cited reports of mistreatment of Kurds by Iraqi troops as a possible cause.

The official in Geneva said that the fighting soon spread to other areas, including Sulaymaniyah, and that hospitals in that city were unable to cope with the casualties.

Pierre Mehu, a U.N. spokesman, said reports from the region put the number of casualties at 500. He was unable to furnish a breakdown of the deaths and injuries. Other U.N. officials in Geneva said the Kurdish rebels on Thursday had taken control of about 90% of Sulaymaniyah.

These U.N. officials said they had received reports that Sulaymaniyah was shelled and strafed by Iraqi helicopters, but that administrative buildings remained in the hands of the local Kurdish officials.

Barzani, the Kurdish leader in Baghdad, put the number of casualties on both sides at 100. Correspondents from U.S. newspapers visiting Irbil on Friday said they were told by Kurdish rebels that there were 100 casualties in that city alone. Coffins were being carried by taxi through the streets of the city of 750,000, capital of the Kurdish region.

These reporters said the building containing the offices of the Baghdad central government had been burned. The structure stands across the street from another government building that was set afire during the Kurdish uprising in March.

Barzani heads the Kurdish Democratic Party, one of eight groups in the Iraqi Kurdistan Front, which is negotiating with Hussein’s regime toward an agreement on autonomy for the Kurdish region.

Barzani contended that the fighting had been exploited by groups opposing those negotiations.

In Washington, a Bush Administration official, speaking on condition of anonymity, said the United States was receiving conflicting reports about the fighting and was checking the possibility that some Kurdish factions were “moving against others out of vengeance.”

The Iraqi superguns and the Kurds dominated discussion at the United Nations as the five permanent members of the Security Council--the United States, Britain, France, the Soviet Union and China--met for a private briefing on Iraq’s nuclear capabilities from Rolf Ekeus, executive chairman of the special U.N. commission charged with identifying and eliminating Iraq’s weapons of mass destruction--nuclear, biological and chemical arms, as well as missiles.

After the meeting, Ekeus put the United Nations’ continuing search for nuclear weapons components into perspective.

In recent days, he said, the Baghdad government has become more cooperative in amplifying its earlier nuclear disclosures. But Ekeus said more information is needed.

“There is more to be known,” he said. Western diplomats who attended the meeting said Ekeus laid out a number of subjects that still need exploring when other inspection teams return to Iraq.

Times staff writers James Flanigan in Baghdad, James Gerstenzang in Athens and John M. Broder in Washington contributed to this report.