NATO forces took control of the last major unprotected cities in Kosovo a day ahead of schedule today, but with less than one-third of the full allied peacekeeping contingent in the province, acts of violence by both departing Serbs and newly empowered ethnic Albanians continued to proliferate.

With the withdrawal of all Yugoslav army and Serbian police forces expected to be complete by midnight tonight in central Kosovo -- the second of three zones mapped by Yugoslav and NATO generals under last week's peace agreement -- the roads in and out of the province remain a chaotic illustration of the dramatic shift in the balance of power here.

Serbian residents continued to pack their cars and tractor-pulled carts and drive north, creating a traffic jam that reportedly stretched 40 miles beyond the Kosovo border into Serbia proper. International aid agencies estimate that 60,000 Serbs have fled Kosovo -- nearly 30 percent of the prewar population. They feared revenge from Kosovo Liberation Army rebels or ethnic Albanians who were targets of brutal Serbian repression during the 78-day NATO aerial bombing campaign.

Serbian civilians have appealed to the allied Kosovo Protection Force, or KFOR, for protection. Today, NATO forces, including armored personnel carriers, escorted one group of departing Serbs from the southwestern town of Prizren to Pristina, the Kosovo capital, on their way to Serbia.

"As of now, KFOR is in every major town in Kosovo," said a NATO spokesman, Lt. Col. Robin Clifford, adding, "What we need now is cool heads and calmness." NATO plans to deploy about 50,000 troops in Kosovo, a province of Serbia, Yugoslavia's dominant republic. About 16,000 troops are now in the province, according to NATO.

The tide of ethnic Albanian refugees returning to Kosovo from Albania and Macedonia has swelled so dramatically that international aid officials say some camps around the Albanian border town of Kukes could be emptied within a week. In the past four days more than 65,000 of the more than 800,000 refugees who fled Kosovo have returned to their homeland despite warnings that many villages have been destroyed, food is scarce and mines and booby traps are still present, according to officials of the U.N. High Commissioner for Refugees.

The officials said they are considering dismantling tents at refugee camps in Macedonia and Albania and moving them in several weeks to some of the most devasted areas of Kosovo where refugees will be returning.

NATO officials said the last 700 Yugoslav army forces in central Kosovo would depart by tonight's midnight deadline. Officials also said that the remaining 10,500 Yugoslav forces -- about one-fourth of the 40,000 troops in Kosovo at the end of the NATO air campaign -- will leave by Sunday night's deadline for all Serbian forces to withdraw.

British troops rumbled into the northern Kosovo city of Podujevo today -- a day ahead of schedule at the request of the departing Yugoslav military, according to Clifford. The British forces were greeted by exuberant, flower-tossing crowds like those that have lined the streets in most major towns when allied soldiers arrived.

To the southwest of Podujevo in the town of Srbica, French forces also arrived to joyous crowds. But just a few miles to the west, roads were deserted and the countryside and villages were devoid of people. Former Yugoslav military and police checkpoints behind banks of sandbags were vacant.

With KLA guerrillas expanding their presence in towns and villages and at highway checkpoints across the province, Serbian civilians continued their flight in what NATO and aid officials believe could become a second refugee crisis.

Serbian Deputy Prime Minister Milovan Bojic today blamed NATO forces for the mass exodus of Serbs, saying that the allied troops' failure to provide more protection across the province has created a power vacuum, according to the official Yugoslav news service, Tanjug.

The leader of the Serbian Orthodox Church traveled to several communities in Kosovo with NATO commanders in an effort to persuade his followers to remain in their homes. However, at about the same time, a Serbian special police official, Gen. Obrad Stevanovic, was touring southwestern Kosovo urging civilians to leave, according to German commanders in charge of NATO operations in the region.

In sectors of Kosovo controlled by German and U.S. troops, soldiers continued stripping ethnic Albanian rebels of their weapons, even though NATO and KLA leaders are still haggling over the details of an agreement to demilitarize members of the organization.

In Brussels, NATO's decision-making North Atlantic Council agreed today to provide the U.N. war crimes tribunal with the logistical and military support it needs to visit scenes of alleged atrocities in Kosovo. NATO also agreed that its troops will be responsible for clearing land mines and booby traps, and then sealing the sites off from journalists and other civilians.

Advance teams of investigators from the tribunal have been in Kosovo for several days, armed with a list of about 20 sites previously chosen for their value in the case prosecutors are building against Yugoslav President Slobodan Milosevic and four top aides, who were indicted May 27 on war crimes charges. Since arriving in Kosovo last Saturday, NATO troops have brought as many as 80 other alleged massacre sites to the investigators' attention, officials said.

A British official said Thursday that the number of ethnic Albanians killed by Serbian forces could exceed 10,000, although Louise Arbour, the tribunal's chief prosecutor, today refused to confirm that or any other death-count figure.

Investigators from Britain and the United States will be ready to move to the first list of sites this weekend, and they will be followed by teams from Canada and France, officials said. They said the number of war crimes investigators from about 30 countries will reach 350 within a month, in teams of 15 to 20. Under today's agreement with NATO, allied forces will transport, house, feed and guard the investigators.

Speaking to reporters at NATO headquarters in Brussels, Arbour said that NATO's pledge of help "takes a considerably, and explicitly, more proactive stance in supporting the efforts of the tribunal, including, if need be, on apprehension issues" -- meaning the arrest of war crimes suspects in Kosovo as well as in Bosnia.

The tribunal's deputy prosecutor, Graham Blewitt, said in a telephone interview that "in the past NATO did not appreciate who or what we were -- they saw the tribunal as another humanitarian organization. We had to compete with all the [nongovernmental organizations] for their support. . . . Now we don't have to go begging to them with cup in hand, and spending a lot of time spinning our wheels."

Correspondent Charles Trueheart in Paris contributed to this report.

CAPTION: Serbian civilians flee north from Pristina, Kosovo's capital, with their belongings piled in a farm cart pulled by a tractor. In the background is a house set on fire by departing Serbs.

CAPTION: Yugoslav troops escort a convoy of Serbs through Luzane, a village north of Pristina, as the Serbian exodus from Kosovo continued.