PRISTINA, Yugoslavia (AP) _ With evidence growing of Serb savagery during NATO's bombing campaign, NATO peacekeepers tried to prevent ethnic Albanians from taking out their rage on Serbs and their Christian holy sites.

As Serbs continued to flee Kosovo, the leader of the Serbian Orthodox Church visited the province and joined peacekeepers in pleading with his fellow Serbs to stay in what they consider the cradle of their culture. But a Serbian police general was said to be urging thousands of Serbs in one town to leave.

Meanwhile, President Clinton said he expected Russian and U.S. negotiators to reach agreement today on Russia's role in the Kosovo peacekeeping mission. Negotiators met for the third day in Helsinki, Finland.

Fears grew that ethnic Albanian rebels would seek violent revenge for what was emerging as a frenzy of torture and killing by Serb forces in Kosovo during NATO's 78-day bombardment of Yugoslavia.

Six days into the international military presence in the province, officials who discovered mass graves and killing sites and heard accounts of atrocities estimate that at least 10,000 people were killed by the Serbs.

To ward off retaliatory attacks from ethnic Albanian rebels, NATO stationed a tank to block the winding road leading to the monastery in Decane in western Kosovo and another blocking the Serbian Orthodox monastery's gates.

Inside were huddled 20 monks and a few elderly Serbs who hadn't fled the nearby village. Ethnic Albanian villagers, who said the monastery protected them during the Serb rampage, pledged to defend the monks with their lives.

NATO was too late in Devic, another monastery in the hills of central Kosovo. Television images showed shattered icons and bullet shells. ``UCK'' _ the Albanian initials for the separatist Kosovo Liberation Army _ was scratched into a window.

CNN reported that rebels terrorized the monastery's inhabitants, firing guns next to monk's heads and stripping a nun naked.

There were other reports of attacks. The private Beta news agency in Belgrade said the last two Serbs in the central village of Sofajlija _ a couple in their late 60s _ were found dead Thursday on the doorstep of their home.

In an effort to inspire Serbs not to flee the province, the leader of the Serbian Orthodox Church, Patriarch Pavel, returned to Kosovo Thursday and said he would move his patriarchate to the western Kosovo city of Pec.

``I call on you to be able and persevere to the end because everything will pass,'' he told a large crowd in the courtyard of the 14th century Gracanica monastery.

But the head of the German forces responsible for southwestern Kosovo said that in Orahovac, 30 miles southwest of Pristina, Kosovo's capital, a delegation led by Lt. Col. Gen. Obrad Stevanovic of the federal police was urging the last 3,000 Serbs in town to leave.

The German, Col. Rolf Bescht, said his troops were trying to persuade the Serbs in Orahovac to stay.

The peace plan that ended NATO's bombing campaign requires KLA rebels to demilitarize, but German peacekeepers guarding the border with Albania were letting returning rebels bring their weapons across on Thursday.

Bescht promised to rein in the rebels in and around Prizren, where the German force is based. As of midnight today, he said, KLA members would be barred from carrying weapons in public.

He also said German troops would take over the police stations, which the rebels have held in recent days, ``to make it crystal clear that we are the only force in town.''

Meanwhile, peacekeepers were uncovering more evidence of Serb atrocities against ethnic Albanians, who before the war made up 90 percent of Kosovo's 2.1 million people.

British Foreign Office Minister Geoff Hoon estimated that 10,000 people died in a Serb killing spree during NATO's bombing, adding: ``Tragically, our estimates ... will almost certainly have to be revised upward.''

One of the most grisly reports of slaughter so far came Thursday from Poklek, 20 miles west of Pristina.

Elhame Muqolli, 14, said she and scores of friends and neighbors were herded into a room by Serb police, who threw in a hand grenade, raked the room with machine guns, then set it on fire.

Elhame and five others managed to jump out a window, but 62 people died in the April 17 incident. Their blood dripped through the floor to stain the ceiling of the room below.

The items piled in a basement of a police station in Pristina also spoke of horror: an array of torture instruments, including bats, chains, a pickax and a black hood. An ethnic Albanian resident of the neighborhood who didn't give his name said he and many others had been beaten there. British troops also found sadistic pornography in the room.

What was most chilling, Hoon said, was that the station ``seems to have been just an ordinary police headquarters. In other words, the barbaric acts carried out in this building were probably almost a matter of routine.''

The mounting evidence is likely to add to calls for the arrest of Yugoslav President Slobodan Milosevic, who has been indicted by the international war crimes tribunal in The Hague, Netherlands. But Clinton said Thursday that peacekeepers will take a ``wait and see'' approach toward Milosevic's arrest.

In Helsinki, U.S. and Russian negotiators were trying to define a role for Russia in the peacekeeping mission.

Russia's resolute insistence on an equal footing with NATO is frustrating U.S. efforts to draw Moscow into the Western alliance's plans for pacifying the province.

The matter of Russia's role took on added urgency after Moscow sent 200 troops into Pristina last weekend and gained control of the airport. The Russians are still holed up there, although officials said the Helsinki talks had tentatively settled the matter of NATO's access to the airport.

Clinton said today in Cologne, Germany, that ``almost all the issues'' in the talks had been resolved. ``I expect we'll get this worked out today,'' he said.

In the Macedonian capital, Skopje, meanwhile, a strong explosion destroyed a truck outside the local NATO headquarters. There were no reports of injuries. Macedonia is the staging point for alliance troops heading into Kosovo.