A simmering dispute over free movement within Kosovo erupted in violence today, with French troops fighting back hundreds of ethnic Albanians who were trying to cross into the Serbian part of this northern Kosovo town.

Amid curses, shoving and obscene gestures, dozens of French soldiers kept the ethnic Albanians from crossing a bridge over the Ibar River, while an equally agitated Serbian crowd jeered from the far side. At least four ethnic Albanians were arrested after fighting with soldiers. Three people were injured, including one woman who was driven off in an ambulance after being knocked down.

The violent protest, which continued for several hours, demonstrated the deep-rooted hatred between Kosovo's Serbs and ethnic Albanians. That hatred has started to turn on NATO troops, who are in the region to provide security.

Kosovska Mitrovica, a mining center 25 miles northwest of Pristina that is valued by Serbs and ethnic Albanians, is divided by the river into separate ethnic communities. Since the end of the Kosovo war in June, the central bridge has become a symbol of confrontation, with Serbs preventing ethnic Albanians from returning to live north of the river.

Stray gunshots rang out during the confrontation, and the rival groups separated by the French soldiers traded taunts and hurled rocks at each other. When the soldiers pushed back the ethnic Albanians, they were accused of siding with the Serbs on the other side.

Lt. Meriadic Raffray of the French forces said peacekeepers had been escorting limited numbers of ethnic Albanians across the bridge over the past few days. He accused ethnic Albanian extremists of trying "to provoke a reaction like this."

Local leaders of the Kosovo Liberation Army, the ethnic Albanian guerrilla group being disbanded under an agreement with NATO, led the protest and eventually persuaded the crowd to disperse after the four people arrested were freed.

The violence occurred amid growing concern over the safety of peacekeeping troops. A Russian soldier was shot in the leg Thursday by an unknown sniper. Ethnic Albanians accuse Russian mercenaries of having fought alongside Serbian forces in their campaign of massacres and expulsions against ethnic Albanians that precipitated the NATO air campaign against Yugoslavia.

The Serbs, in turn, have blamed NATO forces for failing to maintain peace or to prevent revenge attacks by ethnic Albanians. Some 160,000 Serbs have fled the province in the past two months.

The KLA leadership, however, told a rally of several thousand people in Podujevo, 18 miles east of Kosovska Mitrovica, that NATO was the ally of the Kosovo people.

"These are allies people respect and will always remember for what they did for us," said Hashim Thaqi, the former rebel now heading an interim ethnic Albanian administration in Kosovo.

He said the KLA would be transformed into a Kosovo army to defend the country when NATO leaves. He also said his leadership supported independence for Kosovo after a three-year transition period. The West, however, has urged Kosovo to pursue autonomy rather than independence from Yugoslavia.

Another popular ethnic Albanian leader, Ibrahim Rugova, also said in an interview with Germany's Der Spiegel magazine that Yugoslavia will never regain control of Kosovo, even if President Slobodan Milosevic is ousted. Rugova, the self-styled president of an unrecognized Kosovo republic, said the Serbs had lost their claim to Kosovo through the repression and acts of brutality committed by the Serb-led Yugoslav army and police before NATO intervened.