Yugoslav troops seized anti-tank mines Friday after a pair of battles with Albanian arms smugglers, in what could signify a dangerous escalation of the fighting in Kosovo.

The soldiers said it was the first time they have found smugglers with the powerful mines. Four smugglers were killed in the fighting.Government and ethnic Albanian sources reported scattered clashes throughout the rebellious province, where Albanian rebels of the Kosovo Liberation Army are fighting for independence from Serbia, the dominant of two republics that make up the remainder of Yugoslavia.

The six-nation Contact Group, which coordinates international policy in the Balkans, on Wednesday called for significant autonomy but not independence for Kosovo. The group also called for an immediate cease-fire after a meeting in Bonn, Germany.

But Serb and Albanian sources reported sharp fighting Friday in several areas along the Albanian border, over which ethnic Albanians smuggle weapons into the province.

At the scene of one battle - near the border town of Kosare, 53 miles southwest of Kosovo's capital, Pristina - reporters saw bodies of two suspected smugglers lying in the grass.

In addition to the mines, Yugoslav troops seized a large quantity of weapons, including rifles, machine guns, and ammunition. A captured smuggler, Zef Kqiraj, claimed he bought the weapons from an Albanian army sergeant.

On Friday, hundreds of armed Kosovo Albanians fortified the village of Pantina west of Pristina, fearing attack from Serb neighbors.

Villagers said Serbs in nearby Svinjare had burned down four Albanian houses after their occupants had fled.

Serb civilians, some toting rifles, blocked reporters from entering Svinjare.

Serb police arrested 11 ethnic Albanians on Friday for allegedly organizing a secret guerrilla unit in the southern towns of Urosevac and Kacanik. The Serb Media Center said 22 other suspected KLA members eluded arrest in dawn raids in the two towns.

Serb sources also said that Albanian militants attacked police early Friday in the village of Dolac, 28 miles west of Pristina, but were driven off with "significant losses."

Meanwhile in London, British officials said Friday that the Contact Group - made up of the United States, Britain, France, Germany, Italy and Russia - had established a number of working principles for a future agreement in the region.

The officials said the principles include guaranteed political representation for all Kosovo's citizens, a freezing of the national boundaries of the province's neighbors, and an agreement that neither Kosovo's authorities nor Yugoslav officials would seek to change the territory's status unilaterally.

The member countries also warned the KLA that they would crack down on financial support the rebels receive from Albanian communities abroad.

The Contact Group's backing for significant autonomy for Kosovo will disappoint the increasing number of ethnic Albanian militants fighting for independence.