Serb forces blasted ethnic Albanian separatists with mortar fire Tuesday as they tried to dislodge them from a strategic Kosovo coal mine.

Serb police kept access blocked to the area around the mine and nearby village of Belacevac, six miles west of the provincial capital, Pristina. Heavy mortars and other artillery echoed as clouds of black smoke billowed from two locations near the village.On Monday, a three-pronged Serb attack sent more than 8,000 people fleeing their homes in Belacevac and the neighboring village of Hade. By evening, police and other paramilitary Serb forces had advanced within 600 feet of Belacevac.

The Serbs want to retake the Belacevac open-pit mine, which fell to the ethnic Albanians' Kosovo Liberation Army last week. The mine supplies coal to the nearby Obilic power plant, which provides electricity to most of Kosovo.

In New York, Human Rights Watch blamed both sides - although it primarily targeted the Serbs - of violating human rights in the area.

In a statement, the private watchdog group said it had "powerful evidence" that Serb police "summarily executed" an unspecified number of ethnic Albanians between February and May.

It also said eyewitnesses reported the rape of three women in Ljubenic and said helicopters with Red Cross markings fired on fleeing refugees on at least two occasions in early June. The report did not explain why the helicopters had the markings.