NATO says it's investigating the circumstances surrounding an attack it carried out inside Kosovo which it says was on a convoy of military vehicles.

Serbian reports say NATO's planes hit a column of cars and tractors carrying Kosovo Albanian refugees.

According to the French news agency, at least twenty refugees were killed.

The agency's reporter saw the bodies of men, women and a child as well as bombed-out tractors and houses in the village of Meha.

Pictures taken by a Reuters news agency photographer showed bodies lying on the road amid mattresses and pillows.

Serbian television, recalling the accidental attack on a train on Monday, says that NATO has now twice in three days killed innocent civilians.

But in a statement from its headquarters in Brussels, NATO said its aircraftattacked military vehicles near a bridge east of Djakovica after coming under fire from the ground.

United States and German officials say there's evidence of a subsequent assault on refugees by Yugoslav soldiers.