RANIYAH, IRAQ, JUNE 3 -- In the most serious outbreak of violence since an April cease-fire, Kurds and Iraqi government forces have clashed in three northern Iraqi cities, news reports and witnesses said today.

Four Kurds and two Iraqi officials of the ruling Baath Party were killed in one demonstration in the provincial capital of Dahuk in which Kurds urged U.S. troops to stay in northern Iraq, Turkey's government-controlled Anatolia News Agency reported.

However, the violence took place outside a security zone policed by allied troops, and neither U.S. nor U.N. forces intervened.

Last week, crowds of Kurdish men clashed with Iraqi security forces in Sulaymaniyah and Irbil, two large Kurdish cities, witnesses said today. At least seven Republican Guards were killed and government offices were destroyed, the witnesses said.

Many Kurds believe Iraq will move against them when the allies leave northern Iraq. The allies established a security zone for Kurds who fled after their anti-government uprising failed. Recent statement's by U.S. officials have fueled Kurdish fears that the United States is preparing to withdraw.

{In Paris, a French group investigating damage caused by the Persian Gulf War said Monday that up to 250,000 people may have been killed in Iraq during the war and civil unrest that immediately followed, Reuter reported.

{"The Iraqi government is clearly trying to minimize losses . . . but the figures given to us were that between 35,000 and 45,000 civilians, and between 85,000 and 110,000 soldiers were killed in the gulf war," said lawyer Dominique Tricaud after returning from Iraq.

{"The authorities were even vaguer when it came to the civil war which followed, but the figures given for those killed, most of them in southern Iraq and the overwhelming majority of them civilians, ranged from 25,000 to 100,000 dead," said Tricaud. He added that as far as he knew, it was the first time Iraqi officials had provided such detailed figures.

{The Iraqis previously have declined to release information on casualties, not only from the gulf war but also the eight-year Iran-Iraq war.

{The French group was believed to have stayed in Iraq for fewer than five days, Washington Post correspondent Jonathan C. Randal reported from Paris, and the statistics Tricaud and others provided could not be verified. Tricaud is a member of an organization known as The Truth About the Gulf War.}

The four Kurds killed Sunday evening died in a demonstration outside offices of the ruling Baath Party when shots were fired from inside the building, Anatolia News Agency reported. The crowd then attacked the building with sticks and stones and killed two party officials, Anatolia said, quoting witnesses.

Kurdish leaders in Raniyah, a small town 80 miles north of Sulaymaniyah, said seven Kurds and three Iraqis were killed in the clash in Dahuk. Neither their report nor that of Anatolia could be independently confirmed.

About 2,000 Kurds demonstrated outside the police station in Dahuk earlier in the day on Sunday. About 50 or 60 Iraqi officers were hurt in the clash, Anatolia said.

Officially, security is in the hands of Iraqi police and representatives of Kurdish rebels.

In Irbil, west of Sulaymaniyah, crowds of young men have been gathering every night for a week to protest attempts by Iraqi security forces to round up deserters, witnesses said.

Riots also have occurred in Zakhu, a city in the allied security zone.