By MELISSA EDDY Associated Press Writer

PRISTINA, Yugoslavia (AP) - Explosions rocked the American sector of eastern Kosovo, killing two people and injuring four, NATO said today. A private Serb news agency described the incident as a mortar attack on two Serb villages.

Eight to 10 blasts occurred Tuesday evening near Donje Budrige village, three miles south of Gnjilane, according to Pfc. William Patterson of the U.S. military press office at Camp Bondsteel. He did not say whether the victims were Serbs or ethnic Albanians.

Patterson said one critically injured victim was evacuated to an American military clinic near Urosevac.

``Two civilians were killed and four were wounded, one of them critically,'' said Captain John
Sweeney, a U.S. KFOR spokesman at the American base of Camp Bondsteel, outside
Urosevac.

``We believe the explosions were caused by mortars. One of the dead is a woman. All of the rest
of the victims are male and we believe all are Serbs.''

The most seriously wounded victim was now in stable condition at Camp Bondsteel, the KFOR
spokesman added.

In Belgrade, the private Beta news agency quoted local residents as saying 15 mortars were fired Tuesday evening at the adjacent Serb villages of Donje Budrige and Partesa. Beta, quoting a local ham radio operator, put the casualty toll at one dead and several wounded. All were Serbs and most were from Donje Budrige, Beta said. KFOR peacekeepers Wednesday were examining the mortar bomb craters in Donja Budriga to determine the distance and direction from which the rounds were fired, hoping to identify and apprehend the attackers.

The agency said U.S. helicopters hovered over the area after the attack and angry villagers blocked the roads to demand better protection by American forces.

The explosions occurred one day after Russian soldiers patrolling in the American sector shot and killed three Serbs after they disregarded orders to stop beating two wounded Albanians and instead opened fire on the peacekeepers.

Gniljane, about 25 miles southeast of Kosovo's capital, Pristina, is in the U.S. sector of
peacekeeping responsibility. Significant numbers of Russian troops also patrol there.

The area, which borders the rest of Serbia, has been one of the least settled in Kosovo since
peacekeepers deployed here in mid-June.

Kidnappings, murder and arson have continued, with both Serbs and ethnic Albanians caught up
in a spiral of post-war revenge and criminality.

In another probable mortar attack in the U.S. sector, there were 12 explosions in the town of
Petrovce Tuesday.

No one was hurt, but Russian troops operating in the area seized one suspect who was found with
safety pins from mortar bombs in his pocket, U.S. liaison officer Steve Stover said.

Those incidents have raised tensions in Kosovo before the scheduled Sept. 19 demilitarization of the rebel Kosovo Liberation Army.

Yugoslavia's crackdown on the KLA and ethnic Albanians in Kosovo triggered the 78-day NATO bombing campaign.

The peacekeepers' worst fear is that shadowy ethnic militias may be forming beyond the control of
local political or military leaders and joining up with criminal opportunists to prolong instability in
Kosovo.

NATO stopped its air bombardment on Yugoslavia after President Slobodan Milosevic accepted a U.N.-sanctioned peace agreement, which provided for 40,000 NATO and Russian peacekeepers to maintain security in Kosovo.

In Pristina, 200 ethnic Albanians from the northwestern city of Kosovska Mitrovica gathered today outside U.N. headquarters to demand that French peacekeepers allow Albanians to return to their homes in the Serb-controlled part of town.

The French have restricted across to the two sectors, separated by the Ibar River, to prevent violence - even though the move means many ethnic Albanians cannot return to their homes.

U.N. security guards closed the main gate to the headquarters while protesters held up signs reading ``Free Mitrovica'' and ``Don't allow the division of Mitrovica.''

``If NATO does not help us, we'll become NATO ourselves,'' said one of the protesters, Sheremet Ymeri, 31. ``We'll take up weapons and free our homes.''

The incidents occurred as Russia stepped up its criticism of NATO's role in Kosovo. In a statement Tuesday to the ITAR-Tass news agency, Col. Gen. Leonid Ivashov accused NATO of failing ``to ensure the security of people of different nationalities residing in the territory, primarily non-Albanians.''

Ivashov said Moscow was dissatisfied with the pace of disarming the KLA. The United States, however, has offered the KLA a new role as the ``Kosovo Corps,'' a lightly armed force that would respond to natural disasters and assist in security missions.

``There is no serious disarmament of the KLA, and it is impossible to speak about regional stability without that,'' Ivashov said.

Russia's complaints are expected to figure in talks in Moscow next week between Russian Defense Minister Igor Sergeyev and U.S. Defense Secretary William Cohen.

International attempts to bring peace to Kosovo have been confounded by a wave of violence by ethnic Albanians seeking revenge against Serbs for the 18-month crackdown that left 10,000 dead and hundreds of thousands displaced before NATO intervened.

Most of the more than 200,000 Kosovo Serbs have fled since NATO troops replaced Serb forces in the province.