Three Serb policemen have been killed in a explosion believed to have been caused by two anti-tank mines.
The attack, in Lucane, Yugoslavia, was expected to add to tensions between Serbs and ethnic Albanian militants.
It came two days after a bomb attack on a bus inside Kosovo that killed at least seven people and injured another 43.
Milovan Coguric, a Yugoslav Defence Ministry official in Bujanovac, near Lucane, identified the three policemen killed as Milomir Jeremic, Milenko Zivkovic and Boban Mitic.
"This is a monstrous act by (ethnic) Albanian terrorists," Mr Coguric said.
Today's blast destroyed the vehicle the policemen were driving near Lucane just outside a three-mile buffer zone bordering Kosovo.
In Lucane, Serb police and ethnic Albanian militants are only separated by a river.
The village of about 500 houses has been almost deserted after most local people left.