NATO officials and local residents say the bodies of up to 350 ethnic Albanians may be buried in mass graves and heaped in ash piles in and around this mountain village in western Kosovo, where witnesses report that hundreds were slaughtered by Serbian security forces in April.

If confirmed by war crimes investigators, the Ljubenic area could contain the largest concentration of mass graves discovered in Kosovo since the end of NATO's 78-day air war brought the withdrawal of Yugoslav forces and halted their campaign of expulsions and killing of the province's ethnic Albanian majority.

Italian troops serving with the NATO peace force in Kosovo have cordoned off part of the village and the foothills of nearby mountains, which villagers and officials said were heavily mined.

NATO officials said the estimated number of bodies buried here was based on reports from sources they would not identify. But villagers said Italian soldiers and other NATO peacekeeping troops had been scouring the area since at least Wednesday, and Danish troops -- who often assist war crimes investigators in The Hague -- have also been in the area.

On Thursday in Ljubenic, four decomposing bodies lay in the open near two large ash heaps that contained bone fragments and bits of clothing and shoes. Today, an area where residents said the first of two waves of Serbian violence began in April was littered with traces of blood, coats, shoes and empty wallets.

"Very terrible things happened here," said Sali Huskaj, one of Ljubenic's residents.

Villagers say the killings began on April 1, when Yugoslav army troops surrounded Ljubenic, a town of red-topped brick and stone houses just south of Pec, one of the cities most heavily damaged by Yugoslav and Serbian forces.

Several survivors said today that Yugoslav troops and Serbian paramilitary forces ordered residents to assemble at the base of the hillside village, shouting, "Go to Clinton!" About 70 men were separated from more than 200 women and children, the witnesses said, and were lined up and confronted by three soldiers carrying machine guns.

The soldiers sprayed the men with machine-gun fire until they all fell to the ground, then continued firing on them as they lay crumpled on the side of the gravel road leading into the village, witnesses said.

Gani Bushati, 57, and Demush Ukshinaj, 64, said they and nine others survived the assault by lying quietly in a heap near the back of the group. After an hour and half, Bushati said 10 of them fled to a village controlled by the rebel Kosovo Liberation Army; the 11th survivor died of his injuries near the village.

Bushati had documents from a hospital in Albania, where he later fled, indicating that he suffered 36 bullet wounds on his right side, leg and ankle. He pulled down his pants to display the wounds for reporters.

"I cannot believe I lived," he said.

None of the villagers interviewed today said they knew what had happened to the bodies of the men executed.

Almost a week later, on April 7, the Serbs hit surrounding villages with a more brutal offensive than before. Huskaj and others said more than 1,000 ethnic Albanians fled in five separate groups toward the mountains on the road that runs through Ljubenic, which is near Kosovo's border with both Albania and the Yugoslav republic of Montenegro.

Their path of escape led them toward Serbian forces patrolling the border, however, and Huskaj and other villagers estimated that between 180 to 300 people were killed on the mountainside that day. One survivor, Ramadan Veselaj, who had fled into the hills after the April 1 massacre, said he saw nine people shot in the second wave of killings.

"Everyone was running for their life," Veselaj said. "We did not know what else to do."

Huskaj said villagers and NATO soldiers have found about 120 corpses buried in several locations up the mountain from Ljubenic, but the danger of mines has limited the search. Twenty-two bodies were discovered on Thursday alone, he said.

Ljubenic was included earlier this year on a State Department list of sites in Kosovo where Yugoslav forces are believed to have killed 100 or more people. It was also the location of a May 1998 mass execution in which eight ethnic Albanians were killed, including seven from the same family.

CAPTION: An Italian NATO soldier looks at photos of Kosovo Albanians found in a field close to the site of a suspected mass grave near the village of Ljubenic.